auto merge of #5208 : Ms2ger/servo/USVString, r=jdm

14 files changed, 477 insertions, 151 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index fa6c0475000..583a0233c7f 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -419,7 +419,8 @@ def typeIsSequenceOrHasSequenceMember(type):
     return False
 
 def typeNeedsRooting(type, descriptorProvider):
-    return type.isGeckoInterface() and descriptorProvider.getDescriptor(type.name).needsRooting
+    return (type.isGeckoInterface() and
+            descriptorProvider.getDescriptor(type.unroll().inner.identifier.name).needsRooting)
 
 
 def union_native_type(t):
@@ -716,6 +717,32 @@ def getJSToNativeConversionInfo(type, descriptorProvider, failureCode=None,
 
         return handleOptional(conversionCode, CGGeneric(declType), default)
 
+    if type.isUSVString():
+        assert not isEnforceRange and not isClamp
+
+        conversionCode = (
+            "match FromJSValConvertible::from_jsval(cx, ${val}, ()) {\n"
+            "    Ok(strval) => strval,\n"
+            "    Err(_) => { %s },\n"
+            "}" % exceptionCode)
+
+        if defaultValue is None:
+            default = None
+        elif isinstance(defaultValue, IDLNullValue):
+            assert type.nullable()
+            default = "None"
+        else:
+            assert defaultValue.type.tag() in (IDLType.Tags.domstring, IDLType.Tags.usvstring)
+            default = 'USVString("%s".to_owned())' % defaultValue.value
+            if type.nullable():
+                default = "Some(%s)" % default
+
+        declType = "USVString"
+        if type.nullable():
+            declType = "Option<%s>" % declType
+
+        return handleOptional(conversionCode, CGGeneric(declType), default)
+
     if type.isByteString():
         assert not isEnforceRange and not isClamp
 
@@ -1085,6 +1112,11 @@ def getRetvalDeclarationForType(returnType, descriptorProvider):
         if returnType.nullable():
             result = CGWrapper(result, pre="Option<", post=">")
         return result
+    if returnType.isUSVString():
+        result = CGGeneric("USVString")
+        if returnType.nullable():
+            result = CGWrapper(result, pre="Option<", post=">")
+        return result
     if returnType.isByteString():
         result = CGGeneric("ByteString")
         if returnType.nullable():
@@ -4646,6 +4678,7 @@ class CGBindingRoot(CGThing):
             'dom::bindings::proxyhandler::{fill_property_descriptor, get_expando_object}',
             'dom::bindings::proxyhandler::{get_property_descriptor}',
             'dom::bindings::str::ByteString',
+            'dom::bindings::str::USVString',
             'libc',
             'util::str::DOMString',
             'std::borrow::ToOwned',
diff --git a/components/script/dom/bindings/codegen/parser/WebIDL.py b/components/script/dom/bindings/codegen/parser/WebIDL.py
index 7474f56baa2..a40c563ae35 100644
--- a/components/script/dom/bindings/codegen/parser/WebIDL.py
+++ b/components/script/dom/bindings/codegen/parser/WebIDL.py
@@ -204,7 +204,7 @@ class IDLObject(object):
             deps.add(self.filename())
 
         for d in self._getDependentObjects():
-            deps = deps.union(d.getDeps(visited))
+            deps.update(d.getDeps(visited))
 
         return deps
 
@@ -338,7 +338,10 @@ class IDLUnresolvedIdentifier(IDLObject):
 
         assert len(name) > 0
 
-        if name[:2] == "__" and name != "__content" and name != "___noSuchMethod__"  and not allowDoubleUnderscore:
+        if name == "__noSuchMethod__":
+            raise WebIDLError("__noSuchMethod__ is deprecated", [location])
+
+        if name[:2] == "__" and name != "__content" and not allowDoubleUnderscore:
             raise WebIDLError("Identifiers beginning with __ are reserved",
                               [location])
         if name[0] == '_' and not allowDoubleUnderscore:
@@ -448,7 +451,59 @@ class IDLIdentifierPlaceholder(IDLObjectWithIdentifier):
         obj = self.identifier.resolve(scope, None)
         return scope.lookupIdentifier(obj)
 
-class IDLExternalInterface(IDLObjectWithIdentifier):
+class IDLExposureMixins():
+    def __init__(self, location):
+        # _exposureGlobalNames are the global names listed in our [Exposed]
+        # extended attribute.  exposureSet is the exposure set as defined in the
+        # Web IDL spec: it contains interface names.
+        self._exposureGlobalNames = set()
+        self.exposureSet = set()
+        self._location = location
+        self._globalScope = None
+
+    def finish(self, scope):
+        assert scope.parentScope is None
+        self._globalScope = scope
+
+        # Verify that our [Exposed] value, if any, makes sense.
+        for globalName in self._exposureGlobalNames:
+            if globalName not in scope.globalNames:
+                raise WebIDLError("Unknown [Exposed] value %s" % globalName,
+                                  [self._location])
+
+        if len(self._exposureGlobalNames) == 0:
+            self._exposureGlobalNames.add(scope.primaryGlobalName)
+
+        globalNameSetToExposureSet(scope, self._exposureGlobalNames,
+                                   self.exposureSet)
+
+    def isExposedInWindow(self):
+        return 'Window' in self.exposureSet
+
+    def isExposedInAnyWorker(self):
+        return len(self.getWorkerExposureSet()) > 0
+
+    def isExposedInSystemGlobals(self):
+        return 'BackstagePass' in self.exposureSet
+
+    def isExposedInSomeButNotAllWorkers(self):
+        """
+        Returns true if the Exposed extended attribute for this interface
+        exposes it in some worker globals but not others.  The return value does
+        not depend on whether the interface is exposed in Window or System
+        globals.
+        """
+        if not self.isExposedInAnyWorker():
+            return False
+        workerScopes = self.parentScope.globalNameMapping["Worker"]
+        return len(workerScopes.difference(self.exposureSet)) > 0
+
+    def getWorkerExposureSet(self):
+        workerScopes = self._globalScope.globalNameMapping["Worker"]
+        return workerScopes.intersection(self.exposureSet)
+
+
+class IDLExternalInterface(IDLObjectWithIdentifier, IDLExposureMixins):
     def __init__(self, location, parentScope, identifier):
         raise WebIDLError("Servo does not support external interfaces.",
                           [self.location])
@@ -511,7 +566,7 @@ def globalNameSetToExposureSet(globalScope, nameSet, exposureSet):
     for name in nameSet:
         exposureSet.update(globalScope.globalNameMapping[name])
 
-class IDLInterface(IDLObjectWithScope):
+class IDLInterface(IDLObjectWithScope, IDLExposureMixins):
     def __init__(self, location, parentScope, name, parent, members,
                  isKnownNonPartial):
         assert isinstance(parentScope, IDLScope)
@@ -546,13 +601,9 @@ class IDLInterface(IDLObjectWithScope):
         self.totalMembersInSlots = 0
         # Tracking of the number of own own members we have in slots
         self._ownMembersInSlots = 0
-        # _exposureGlobalNames are the global names listed in our [Exposed]
-        # extended attribute.  exposureSet is the exposure set as defined in the
-        # Web IDL spec: it contains interface names.
-        self._exposureGlobalNames = set()
-        self.exposureSet = set()
 
         IDLObjectWithScope.__init__(self, location, parentScope, name)
+        IDLExposureMixins.__init__(self, location)
 
         if isKnownNonPartial:
             self.setNonPartial(location, parent, members)
@@ -592,17 +643,7 @@ class IDLInterface(IDLObjectWithScope):
                               "declaration" % self.identifier.name,
                               [self.location])
 
-        # Verify that our [Exposed] value, if any, makes sense.
-        for globalName in self._exposureGlobalNames:
-            if globalName not in scope.globalNames:
-                raise WebIDLError("Unknown [Exposed] value %s" % globalName,
-                                  [self.location])
-
-        if len(self._exposureGlobalNames) == 0:
-            self._exposureGlobalNames.add(scope.primaryGlobalName)
-
-        globalNameSetToExposureSet(scope, self._exposureGlobalNames,
-                                   self.exposureSet)
+        IDLExposureMixins.finish(self, scope)
 
         # Now go ahead and merge in our partial interfaces.
         for partial in self._partialInterfaces:
@@ -681,6 +722,17 @@ class IDLInterface(IDLObjectWithScope):
                                    self.parent.identifier.name),
                                   [self.location, self.parent.location])
 
+            # Interfaces which have interface objects can't inherit
+            # from [NoInterfaceObject] interfaces.
+            if (self.parent.getExtendedAttribute("NoInterfaceObject") and
+                not self.getExtendedAttribute("NoInterfaceObject")):
+                raise WebIDLError("Interface %s does not have "
+                                  "[NoInterfaceObject] but inherits from "
+                                  "interface %s which does" %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
         for iface in self.implementedInterfaces:
             iface.finish(scope)
 
@@ -718,9 +770,13 @@ class IDLInterface(IDLObjectWithScope):
 
         ctor = self.ctor()
         if ctor is not None:
+            assert len(ctor._exposureGlobalNames) == 0
+            ctor._exposureGlobalNames.update(self._exposureGlobalNames)
             ctor.finish(scope)
 
         for ctor in self.namedConstructors:
+            assert len(ctor._exposureGlobalNames) == 0
+            ctor._exposureGlobalNames.update(self._exposureGlobalNames)
             ctor.finish(scope)
 
         # Make a copy of our member list, so things that implement us
@@ -921,10 +977,15 @@ class IDLInterface(IDLObjectWithScope):
                 list(i.location for i in
                      self.interfacesBasedOnSelf if i.parent == self))
 
-
         for member in self.members:
             member.validate()
 
+            if self.isCallback() and member.getExtendedAttribute("Replaceable"):
+                raise WebIDLError("[Replaceable] used on an attribute on "
+                                  "interface %s which is a callback interface" %
+                                  self.identifier.name,
+                                  [self.location, member.location])
+
             # Check that PutForwards refers to another attribute and that no
             # cycles exist in forwarded assignments.
             if member.isAttr():
@@ -966,10 +1027,25 @@ class IDLInterface(IDLObjectWithScope):
 
         if (self.getExtendedAttribute("Pref") and
             self._exposureGlobalNames != set([self.parentScope.primaryGlobalName])):
-            raise WebIDLError("[Pref] used on an member that is not %s-only" %
+            raise WebIDLError("[Pref] used on an interface that is not %s-only" %
+                              self.parentScope.primaryGlobalName,
+                              [self.location])
+
+        if (self.getExtendedAttribute("CheckPermissions") and
+            self._exposureGlobalNames != set([self.parentScope.primaryGlobalName])):
+            raise WebIDLError("[CheckPermissions] used on an interface that is "
+                              "not %s-only" %
                               self.parentScope.primaryGlobalName,
                               [self.location])
 
+        # Conditional exposure makes no sense for interfaces with no
+        # interface object, unless they're navigator properties.
+        if (self.isExposedConditionally() and
+            not self.hasInterfaceObject() and
+            not self.getNavigatorProperty()):
+            raise WebIDLError("Interface with no interface object is "
+                              "exposed conditionally",
+                              [self.location])
 
     def isInterface(self):
         return True
@@ -1151,10 +1227,11 @@ class IDLInterface(IDLObjectWithScope):
                 self.parentScope.globalNames.add(self.identifier.name)
                 self.parentScope.globalNameMapping[self.identifier.name].add(self.identifier.name)
                 self._isOnGlobalProtoChain = True
-            elif (identifier == "NeedNewResolve" or
+            elif (identifier == "NeedResolve" or
                   identifier == "OverrideBuiltins" or
                   identifier == "ChromeOnly" or
                   identifier == "Unforgeable" or
+                  identifier == "UnsafeInPrerendering" or
                   identifier == "LegacyEventInit"):
                 # Known extended attributes that do not take values
                 if not attr.noArguments():
@@ -1284,7 +1361,7 @@ class IDLInterface(IDLObjectWithScope):
 
     def _getDependentObjects(self):
         deps = set(self.members)
-        deps.union(self.implementedInterfaces)
+        deps.update(self.implementedInterfaces)
         if self.parent:
             deps.add(self.parent)
         return deps
@@ -1292,6 +1369,13 @@ class IDLInterface(IDLObjectWithScope):
     def hasMembersInSlots(self):
         return self._ownMembersInSlots != 0
 
+    def isExposedConditionally(self):
+        return (self.getExtendedAttribute("Pref") or
+                self.getExtendedAttribute("ChromeOnly") or
+                self.getExtendedAttribute("Func") or
+                self.getExtendedAttribute("AvailableIn") or
+                self.getExtendedAttribute("CheckPermissions"))
+
 class IDLDictionary(IDLObjectWithScope):
     def __init__(self, location, parentScope, name, parent, members):
         assert isinstance(parentScope, IDLScope)
@@ -1486,7 +1570,7 @@ class IDLType(IDLObject):
         'any',
         'domstring',
         'bytestring',
-        'scalarvaluestring',
+        'usvstring',
         'object',
         'date',
         'void',
@@ -1539,7 +1623,7 @@ class IDLType(IDLObject):
     def isDOMString(self):
         return False
 
-    def isScalarValueString(self):
+    def isUSVString(self):
         return False
 
     def isVoid(self):
@@ -1688,7 +1772,10 @@ class IDLNullableType(IDLType):
         assert not innerType.isVoid()
         assert not innerType == BuiltinTypes[IDLBuiltinType.Types.any]
 
-        IDLType.__init__(self, location, innerType.name)
+        name = innerType.name
+        if innerType.isComplete():
+            name += "OrNull"
+        IDLType.__init__(self, location, name)
         self.inner = innerType
         self.builtin = False
 
@@ -1722,8 +1809,8 @@ class IDLNullableType(IDLType):
     def isDOMString(self):
         return self.inner.isDOMString()
 
-    def isScalarValueString(self):
-        return self.inner.isScalarValueString()
+    def isUSVString(self):
+        return self.inner.isUSVString()
 
     def isFloat(self):
         return self.inner.isFloat()
@@ -1801,7 +1888,7 @@ class IDLNullableType(IDLType):
                                   "be a union type that itself has a nullable "
                                   "type as a member type", [self.location])
 
-        self.name = self.inner.name
+        self.name = self.inner.name + "OrNull"
         return self
 
     def unroll(self):
@@ -1824,6 +1911,10 @@ class IDLSequenceType(IDLType):
         IDLType.__init__(self, location, parameterType.name)
         self.inner = parameterType
         self.builtin = False
+        # Need to set self.name up front if our inner type is already complete,
+        # since in that case our .complete() won't be called.
+        if self.inner.isComplete():
+            self.name = self.inner.name + "Sequence"
 
     def __eq__(self, other):
         return isinstance(other, IDLSequenceType) and self.inner == other.inner
@@ -1846,7 +1937,7 @@ class IDLSequenceType(IDLType):
     def isDOMString(self):
         return False
 
-    def isScalarValueString(self):
+    def isUSVString(self):
         return False
 
     def isVoid(self):
@@ -1885,7 +1976,7 @@ class IDLSequenceType(IDLType):
 
     def complete(self, scope):
         self.inner = self.inner.complete(scope)
-        self.name = self.inner.name
+        self.name = self.inner.name + "Sequence"
         return self
 
     def unroll(self):
@@ -1896,7 +1987,8 @@ class IDLSequenceType(IDLType):
             # Just forward to the union; it'll deal
             return other.isDistinguishableFrom(self)
         return (other.isPrimitive() or other.isString() or other.isEnum() or
-                other.isDate() or other.isNonCallbackInterface() or other.isMozMap())
+                other.isDate() or other.isInterface() or other.isDictionary() or
+                other.isCallback() or other.isMozMap())
 
     def _getDependentObjects(self):
         return self.inner._getDependentObjects()
@@ -1911,6 +2003,10 @@ class IDLMozMapType(IDLType):
         IDLType.__init__(self, location, parameterType.name)
         self.inner = parameterType
         self.builtin = False
+        # Need to set self.name up front if our inner type is already complete,
+        # since in that case our .complete() won't be called.
+        if self.inner.isComplete():
+            self.name = self.inner.name + "MozMap"
 
     def __eq__(self, other):
         return isinstance(other, IDLMozMapType) and self.inner == other.inner
@@ -1936,7 +2032,7 @@ class IDLMozMapType(IDLType):
 
     def complete(self, scope):
         self.inner = self.inner.complete(scope)
-        self.name = self.inner.name
+        self.name = self.inner.name + "MozMap"
         return self
 
     def unroll(self):
@@ -1970,6 +2066,10 @@ class IDLUnionType(IDLType):
     def __eq__(self, other):
         return isinstance(other, IDLUnionType) and self.memberTypes == other.memberTypes
 
+    def __hash__(self):
+        assert self.isComplete()
+        return self.name.__hash__()
+
     def isVoid(self):
         return False
 
@@ -2001,9 +2101,6 @@ class IDLUnionType(IDLType):
                 return typeName(type._identifier.object())
             if isinstance(type, IDLObjectWithIdentifier):
                 return typeName(type.identifier)
-            if (isinstance(type, IDLType) and
-                (type.isArray() or type.isSequence() or type.isMozMap)):
-                return str(type)
             return type.name
 
         for (i, type) in enumerate(self.memberTypes):
@@ -2114,7 +2211,7 @@ class IDLArrayType(IDLType):
     def isDOMString(self):
         return False
 
-    def isScalarValueString(self):
+    def isUSVString(self):
         return False
 
     def isVoid(self):
@@ -2212,8 +2309,8 @@ class IDLTypedefType(IDLType, IDLObjectWithIdentifier):
     def isDOMString(self):
         return self.inner.isDOMString()
 
-    def isScalarValueString(self):
-        return self.inner.isScalarValueString()
+    def isUSVString(self):
+        return self.inner.isUSVString()
 
     def isVoid(self):
         return self.inner.isVoid()
@@ -2313,7 +2410,7 @@ class IDLWrapperType(IDLType):
     def isDOMString(self):
         return False
 
-    def isScalarValueString(self):
+    def isUSVString(self):
         return False
 
     def isVoid(self):
@@ -2387,7 +2484,8 @@ class IDLWrapperType(IDLType):
                     other.isDate())
         if self.isDictionary() and other.nullable():
             return False
-        if other.isPrimitive() or other.isString() or other.isEnum() or other.isDate():
+        if (other.isPrimitive() or other.isString() or other.isEnum() or
+            other.isDate() or other.isSequence()):
             return True
         if self.isDictionary():
             return other.isNonCallbackInterface()
@@ -2405,7 +2503,7 @@ class IDLWrapperType(IDLType):
                     (self.isNonCallbackInterface() or
                      other.isNonCallbackInterface()))
         if (other.isDictionary() or other.isCallback() or
-            other.isSequence() or other.isMozMap() or other.isArray()):
+            other.isMozMap() or other.isArray()):
             return self.isNonCallbackInterface()
 
         # Not much else |other| can be
@@ -2441,6 +2539,13 @@ class IDLWrapperType(IDLType):
         #     Bindings.conf, which is still a global dependency.
         #  2) Changing an interface to a dictionary (or vice versa) with the
         #     same identifier should be incredibly rare.
+        #
+        # On the other hand, if our type is a dictionary, we should
+        # depend on it, because the member types of a dictionary
+        # affect whether a method taking the dictionary as an argument
+        # takes a JSContext* argument or not.
+        if self.isDictionary():
+            return set([self.inner])
         return set()
 
 class IDLBuiltinType(IDLType):
@@ -2466,7 +2571,7 @@ class IDLBuiltinType(IDLType):
         'any',
         'domstring',
         'bytestring',
-        'scalarvaluestring',
+        'usvstring',
         'object',
         'date',
         'void',
@@ -2501,7 +2606,7 @@ class IDLBuiltinType(IDLType):
             Types.any: IDLType.Tags.any,
             Types.domstring: IDLType.Tags.domstring,
             Types.bytestring: IDLType.Tags.bytestring,
-            Types.scalarvaluestring: IDLType.Tags.scalarvaluestring,
+            Types.usvstring: IDLType.Tags.usvstring,
             Types.object: IDLType.Tags.object,
             Types.date: IDLType.Tags.date,
             Types.void: IDLType.Tags.void,
@@ -2535,7 +2640,7 @@ class IDLBuiltinType(IDLType):
     def isString(self):
         return self._typeTag == IDLBuiltinType.Types.domstring or \
                self._typeTag == IDLBuiltinType.Types.bytestring or \
-               self._typeTag == IDLBuiltinType.Types.scalarvaluestring
+               self._typeTag == IDLBuiltinType.Types.usvstring
 
     def isByteString(self):
         return self._typeTag == IDLBuiltinType.Types.bytestring
@@ -2543,8 +2648,8 @@ class IDLBuiltinType(IDLType):
     def isDOMString(self):
         return self._typeTag == IDLBuiltinType.Types.domstring
 
-    def isScalarValueString(self):
-        return self._typeTag == IDLBuiltinType.Types.scalarvaluestring
+    def isUSVString(self):
+        return self._typeTag == IDLBuiltinType.Types.usvstring
 
     def isInteger(self):
         return self._typeTag <= IDLBuiltinType.Types.unsigned_long_long
@@ -2698,9 +2803,9 @@ BuiltinTypes = {
       IDLBuiltinType.Types.bytestring:
           IDLBuiltinType(BuiltinLocation("<builtin type>"), "ByteString",
                          IDLBuiltinType.Types.bytestring),
-      IDLBuiltinType.Types.scalarvaluestring:
-          IDLBuiltinType(BuiltinLocation("<builtin type>"), "ScalarValueString",
-                         IDLBuiltinType.Types.scalarvaluestring),
+      IDLBuiltinType.Types.usvstring:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "USVString",
+                         IDLBuiltinType.Types.usvstring),
       IDLBuiltinType.Types.object:
           IDLBuiltinType(BuiltinLocation("<builtin type>"), "Object",
                          IDLBuiltinType.Types.object),
@@ -2835,10 +2940,10 @@ class IDLValue(IDLObject):
                 raise WebIDLError("Trying to convert unrestricted value %s to non-unrestricted"
                                   % self.value, [location]);
             return self
-        elif self.type.isString() and type.isScalarValueString():
-            # Allow ScalarValueStrings to use default value just like
+        elif self.type.isString() and type.isUSVString():
+            # Allow USVStrings to use default value just like
             # DOMString.  No coercion is required in this case as Codegen.py
-            # treats ScalarValueString just like DOMString, but with an
+            # treats USVString just like DOMString, but with an
             # extra normalization step.
             assert self.type.isDOMString()
             return self
@@ -2923,7 +3028,7 @@ class IDLUndefinedValue(IDLObject):
     def _getDependentObjects(self):
         return set()
 
-class IDLInterfaceMember(IDLObjectWithIdentifier):
+class IDLInterfaceMember(IDLObjectWithIdentifier, IDLExposureMixins):
 
     Tags = enum(
         'Const',
@@ -2936,15 +3041,14 @@ class IDLInterfaceMember(IDLObjectWithIdentifier):
         'Stringifier'
     )
 
+    AffectsValues = ("Nothing", "Everything")
+    DependsOnValues = ("Nothing", "DOMState", "DeviceState", "Everything")
+
     def __init__(self, location, identifier, tag):
         IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+        IDLExposureMixins.__init__(self, location)
         self.tag = tag
         self._extendedAttrDict = {}
-        # _exposureGlobalNames are the global names listed in our [Exposed]
-        # extended attribute.  exposureSet is the exposure set as defined in the
-        # Web IDL spec: it contains interface names.
-        self._exposureGlobalNames = set()
-        self.exposureSet = set()
 
     def isMethod(self):
         return self.tag == IDLInterfaceMember.Tags.Method
@@ -2968,21 +3072,53 @@ class IDLInterfaceMember(IDLObjectWithIdentifier):
         return self._extendedAttrDict.get(name, None)
 
     def finish(self, scope):
-        for globalName in self._exposureGlobalNames:
-            if globalName not in scope.globalNames:
-                raise WebIDLError("Unknown [Exposed] value %s" % globalName,
-                                  [self.location])
-        globalNameSetToExposureSet(scope, self._exposureGlobalNames,
-                                   self.exposureSet)
-        self._scope = scope
+        # We better be exposed _somewhere_.
+        if (len(self._exposureGlobalNames) == 0):
+            print self.identifier.name
+        assert len(self._exposureGlobalNames) != 0
+        IDLExposureMixins.finish(self, scope)
 
     def validate(self):
         if (self.getExtendedAttribute("Pref") and
-            self.exposureSet != set([self._scope.primaryGlobalName])):
+            self.exposureSet != set([self._globalScope.primaryGlobalName])):
             raise WebIDLError("[Pref] used on an interface member that is not "
-                              "%s-only" % self._scope.primaryGlobalName,
+                              "%s-only" % self._globalScope.primaryGlobalName,
+                              [self.location])
+
+        if (self.getExtendedAttribute("CheckPermissions") and
+            self.exposureSet != set([self._globalScope.primaryGlobalName])):
+            raise WebIDLError("[CheckPermissions] used on an interface member "
+                              "that is not %s-only" %
+                              self._globalScope.primaryGlobalName,
                               [self.location])
 
+        if self.isAttr() or self.isMethod():
+            if self.affects == "Everything" and self.dependsOn != "Everything":
+                raise WebIDLError("Interface member is flagged as affecting "
+                                  "everything but not depending on everything. "
+                                  "That seems rather unlikely.",
+                                  [self.location])
+
+    def _setDependsOn(self, dependsOn):
+        if self.dependsOn != "Everything":
+            raise WebIDLError("Trying to specify multiple different DependsOn, "
+                              "Pure, or Constant extended attributes for "
+                              "attribute", [self.location])
+        if dependsOn not in IDLInterfaceMember.DependsOnValues:
+            raise WebIDLError("Invalid [DependsOn=%s] on attribute" % dependsOn,
+                              [self.location])
+        self.dependsOn = dependsOn
+
+    def _setAffects(self, affects):
+        if self.affects != "Everything":
+            raise WebIDLError("Trying to specify multiple different Affects, "
+                              "Pure, or Constant extended attributes for "
+                              "attribute", [self.location])
+        if affects not in IDLInterfaceMember.AffectsValues:
+            raise WebIDLError("Invalid [Affects=%s] on attribute" % dependsOn,
+                              [self.location])
+        self.affects = affects
+
 class IDLConst(IDLInterfaceMember):
     def __init__(self, location, identifier, type, value):
         IDLInterfaceMember.__init__(self, location, identifier,
@@ -3061,6 +3197,8 @@ class IDLAttribute(IDLInterfaceMember):
         self.enforceRange = False
         self.clamp = False
         self.slotIndex = None
+        self.dependsOn = "Everything"
+        self.affects = "Everything"
 
         if static and identifier.name == "prototype":
             raise WebIDLError("The identifier of a static attribute must not be 'prototype'",
@@ -3129,11 +3267,11 @@ class IDLAttribute(IDLInterfaceMember):
 
         if ((self.getExtendedAttribute("Cached") or
              self.getExtendedAttribute("StoreInSlot")) and
-            not self.getExtendedAttribute("Constant") and
-            not self.getExtendedAttribute("Pure")):
+            not self.affects == "Nothing"):
             raise WebIDLError("Cached attributes and attributes stored in "
-                              "slots must be constant or pure, since the "
-                              "getter won't always be called.",
+                              "slots must be Constant or Pure or "
+                              "Affects=Nothing, since the getter won't always "
+                              "be called.",
                               [self.location])
         if self.getExtendedAttribute("Frozen"):
             if (not self.type.isSequence() and not self.type.isDictionary() and
@@ -3158,8 +3296,7 @@ class IDLAttribute(IDLInterfaceMember):
               (identifier == "StoreInSlot" and
                (self.getExtendedAttribute("Throws") or
                 self.getExtendedAttribute("GetterThrows")))):
-            raise WebIDLError("Throwing things can't be [Pure] or [Constant] "
-                              "or [SameObject] or [StoreInSlot]",
+            raise WebIDLError("Throwing things can't be [StoreInSlot]",
                               [attr.location])
         elif identifier == "LenientThis":
             if not attr.noArguments():
@@ -3203,6 +3340,15 @@ class IDLAttribute(IDLInterfaceMember):
                 raise WebIDLError("[PutForwards] takes an identifier",
                                   [attr.location, self.location])
         elif identifier == "Replaceable":
+            if not attr.noArguments():
+                raise WebIDLError("[Replaceable] must take no arguments",
+                                  [attr.location])
+            if not self.readonly:
+                raise WebIDLError("[Replaceable] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[Replaceable] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
             if self.getExtendedAttribute("PutForwards") is not None:
                 raise WebIDLError("[PutForwards] and [Replaceable] can't both "
                                   "appear on the same attribute",
@@ -3250,18 +3396,43 @@ class IDLAttribute(IDLInterfaceMember):
                                   [attr.location, self.location])
         elif identifier == "Exposed":
             convertExposedAttrToGlobalNameSet(attr, self._exposureGlobalNames)
+        elif identifier == "Pure":
+            if not attr.noArguments():
+                raise WebIDLError("[Pure] must take no arguments",
+                                  [attr.location])
+            self._setDependsOn("DOMState")
+            self._setAffects("Nothing")
+        elif identifier == "Constant" or identifier == "SameObject":
+            if not attr.noArguments():
+                raise WebIDLError("[%s] must take no arguments" % identifier,
+                                  [attr.location])
+            self._setDependsOn("Nothing")
+            self._setAffects("Nothing")
+        elif identifier == "Affects":
+            if not attr.hasValue():
+                raise WebIDLError("[Affects] takes an identifier",
+                                  [attr.location])
+            self._setAffects(attr.value())
+        elif identifier == "DependsOn":
+            if not attr.hasValue():
+                raise WebIDLError("[DependsOn] takes an identifier",
+                                  [attr.location])
+            if (attr.value() != "Everything" and attr.value() != "DOMState" and
+                not self.readonly):
+                raise WebIDLError("[DependsOn=%s] only allowed on "
+                                  "readonly attributes" % attr.value(),
+                                  [attr.location, self.location])
+            self._setDependsOn(attr.value())
         elif (identifier == "Pref" or
               identifier == "SetterThrows" or
-              identifier == "Pure" or
               identifier == "Throws" or
               identifier == "GetterThrows" or
               identifier == "ChromeOnly" or
-              identifier == "SameObject" or
-              identifier == "Constant" or
               identifier == "Func" or
               identifier == "Frozen" or
               identifier == "AvailableIn" or
               identifier == "NewObject" or
+              identifier == "UnsafeInPrerendering" or
               identifier == "CheckPermissions" or
               identifier == "BinaryName"):
             # Known attributes that we don't need to do anything with here
@@ -3306,6 +3477,7 @@ class IDLArgument(IDLObjectWithIdentifier):
         self._allowTreatNonCallableAsNull = False
 
         assert not variadic or optional
+        assert not variadic or not defaultValue
 
     def addExtendedAttributes(self, attrs):
         attrs = self.checkForStringHandlingExtendedAttributes(
@@ -3354,9 +3526,9 @@ class IDLArgument(IDLObjectWithIdentifier):
 
         if ((self.type.isDictionary() or
              self.type.isUnion() and self.type.unroll().hasDictionaryType) and
-            self.optional and not self.defaultValue):
-            # Default optional dictionaries to null, for simplicity,
-            # so the codegen doesn't have to special-case this.
+            self.optional and not self.defaultValue and not self.variadic):
+            # Default optional non-variadic dictionaries to null,
+            # for simplicity, so the codegen doesn't have to special-case this.
             self.defaultValue = IDLNullValue(self.location)
         elif self.type.isAny():
             assert (self.defaultValue is None or
@@ -3383,6 +3555,9 @@ class IDLArgument(IDLObjectWithIdentifier):
             deps.add(self.defaultValue)
         return deps
 
+    def canHaveMissingValue(self):
+        return self.optional and not self.defaultValue
+
 class IDLCallbackType(IDLType, IDLObjectWithScope):
     def __init__(self, location, parentScope, identifier, returnType, arguments):
         assert isinstance(returnType, IDLType)
@@ -3442,7 +3617,8 @@ class IDLCallbackType(IDLType, IDLObjectWithScope):
             # Just forward to the union; it'll deal
             return other.isDistinguishableFrom(self)
         return (other.isPrimitive() or other.isString() or other.isEnum() or
-                other.isNonCallbackInterface() or other.isDate())
+                other.isNonCallbackInterface() or other.isDate() or
+                other.isSequence())
 
     def addExtendedAttributes(self, attrs):
         unhandledAttrs = []
@@ -3538,6 +3714,8 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
         self._jsonifier = jsonifier
         self._specialType = specialType
         self._unforgeable = False
+        self.dependsOn = "Everything"
+        self.affects = "Everything"
 
         if static and identifier.name == "prototype":
             raise WebIDLError("The identifier of a static operation must not be 'prototype'",
@@ -3618,7 +3796,7 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
         return self._hasOverloads
 
     def isIdentifierLess(self):
-        return self.identifier.name[:2] == "__" and self.identifier.name != "__noSuchMethod__"
+        return self.identifier.name[:2] == "__"
 
     def resolve(self, parentScope):
         assert isinstance(parentScope, IDLScope)
@@ -3849,16 +4027,32 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
                                   [attr.location, self.location])
         elif identifier == "Exposed":
             convertExposedAttrToGlobalNameSet(attr, self._exposureGlobalNames)
-        elif (identifier == "Pure" or
-              identifier == "CrossOriginCallable" or
+        elif (identifier == "CrossOriginCallable" or
               identifier == "WebGLHandlesContextLoss"):
             # Known no-argument attributes.
             if not attr.noArguments():
                 raise WebIDLError("[%s] must take no arguments" % identifier,
                                   [attr.location])
+        elif identifier == "Pure":
+            if not attr.noArguments():
+                raise WebIDLError("[Pure] must take no arguments",
+                                  [attr.location])
+            self._setDependsOn("DOMState")
+            self._setAffects("Nothing")
+        elif identifier == "Affects":
+            if not attr.hasValue():
+                raise WebIDLError("[Affects] takes an identifier",
+                                  [attr.location])
+            self._setAffects(attr.value())
+        elif identifier == "DependsOn":
+            if not attr.hasValue():
+                raise WebIDLError("[DependsOn] takes an identifier",
+                                  [attr.location])
+            self._setDependsOn(attr.value())
         elif (identifier == "Throws" or
               identifier == "NewObject" or
               identifier == "ChromeOnly" or
+              identifier == "UnsafeInPrerendering" or
               identifier == "Pref" or
               identifier == "Func" or
               identifier == "AvailableIn" or
@@ -3880,7 +4074,7 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
     def _getDependentObjects(self):
         deps = set()
         for overload in self._overloads:
-            deps.union(overload._getDependentObjects())
+            deps.update(overload._getDependentObjects())
         return deps
 
 class IDLImplementsStatement(IDLObject):
@@ -3888,8 +4082,11 @@ class IDLImplementsStatement(IDLObject):
         IDLObject.__init__(self, location)
         self.implementor = implementor;
         self.implementee = implementee
+        self._finished = False
 
     def finish(self, scope):
+        if self._finished:
+            return
         assert(isinstance(self.implementor, IDLIdentifierPlaceholder))
         assert(isinstance(self.implementee, IDLIdentifierPlaceholder))
         implementor = self.implementor.finish(scope)
@@ -3914,6 +4111,8 @@ class IDLImplementsStatement(IDLObject):
                               "interface",
                               [self.implementee.location])
         implementor.addImplementedInterface(implementee)
+        self.implementor = implementor
+        self.implementee = implementee
 
     def validate(self):
         pass
@@ -4044,7 +4243,7 @@ class Tokenizer(object):
         "Date": "DATE",
         "DOMString": "DOMSTRING",
         "ByteString": "BYTESTRING",
-        "ScalarValueString": "SCALARVALUESTRING",
+        "USVString": "USVSTRING",
         "any": "ANY",
         "boolean": "BOOLEAN",
         "byte": "BYTE",
@@ -4053,8 +4252,8 @@ class Tokenizer(object):
         "long": "LONG",
         "object": "OBJECT",
         "octet": "OCTET",
-        "optional": "OPTIONAL",
         "Promise": "PROMISE",
+        "required": "REQUIRED",
         "sequence": "SEQUENCE",
         "MozMap": "MOZMAP",
         "short": "SHORT",
@@ -4339,15 +4538,21 @@ class Parser(Tokenizer):
 
     def p_DictionaryMember(self, p):
         """
-            DictionaryMember : Type IDENTIFIER Default SEMICOLON
+            DictionaryMember : Required Type IDENTIFIER Default SEMICOLON
         """
         # These quack a lot like optional arguments, so just treat them that way.
-        t = p[1]
+        t = p[2]
         assert isinstance(t, IDLType)
-        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
-        defaultValue = p[3]
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 3), p[3])
+        defaultValue = p[4]
+        optional = not p[1]
+
+        if not optional and defaultValue:
+            raise WebIDLError("Required dictionary members can't have a default value.",
+                              [self.getLocation(p, 4)])
 
-        p[0] = IDLArgument(self.getLocation(p, 2), identifier, t, optional=True,
+        p[0] = IDLArgument(self.getLocation(p, 3), identifier, t,
+                           optional=optional,
                            defaultValue=defaultValue, variadic=False,
                            dictionaryMember=True)
 
@@ -4545,7 +4750,7 @@ class Parser(Tokenizer):
 
     def p_AttributeRest(self, p):
         """
-            AttributeRest : ReadOnly ATTRIBUTE Type IDENTIFIER SEMICOLON
+            AttributeRest : ReadOnly ATTRIBUTE Type AttributeName SEMICOLON
         """
         location = self.getLocation(p, 2)
         readonly = p[1]
@@ -4874,6 +5079,7 @@ class Parser(Tokenizer):
                          | INTERFACE
                          | LEGACYCALLER
                          | PARTIAL
+                         | REQUIRED
                          | SERIALIZER
                          | SETTER
                          | STATIC
@@ -4884,6 +5090,13 @@ class Parser(Tokenizer):
         """
         p[0] = p[1]
 
+    def p_AttributeName(self, p):
+        """
+            AttributeName : IDENTIFIER
+                          | REQUIRED
+        """
+        p[0] = p[1]
+
     def p_Optional(self, p):
         """
             Optional : OPTIONAL
@@ -4896,6 +5109,18 @@ class Parser(Tokenizer):
         """
         p[0] = False
 
+    def p_Required(self, p):
+        """
+            Required : REQUIRED
+        """
+        p[0] = True
+
+    def p_RequiredEmpty(self, p):
+        """
+            Required :
+        """
+        p[0] = False
+
     def p_Ellipsis(self, p):
         """
             Ellipsis : ELLIPSIS
@@ -4982,7 +5207,7 @@ class Parser(Tokenizer):
                   | DATE
                   | DOMSTRING
                   | BYTESTRING
-                  | SCALARVALUESTRING
+                  | USVSTRING
                   | ANY
                   | ATTRIBUTE
                   | BOOLEAN
@@ -5255,11 +5480,11 @@ class Parser(Tokenizer):
         """
         p[0] = IDLBuiltinType.Types.bytestring
 
-    def p_PrimitiveOrStringTypeScalarValueString(self, p):
+    def p_PrimitiveOrStringTypeUSVString(self, p):
         """
-            PrimitiveOrStringType : SCALARVALUESTRING
+            PrimitiveOrStringType : USVSTRING
         """
-        p[0] = IDLBuiltinType.Types.scalarvaluestring
+        p[0] = IDLBuiltinType.Types.usvstring
 
     def p_UnsignedIntegerTypeUnsigned(self, p):
         """
@@ -5473,6 +5698,10 @@ class Parser(Tokenizer):
         self._globalScope.primaryGlobalName = "FakeTestPrimaryGlobal"
         self._globalScope.globalNames.add("FakeTestPrimaryGlobal")
         self._globalScope.globalNameMapping["FakeTestPrimaryGlobal"].add("FakeTestPrimaryGlobal")
+        # And we add the special-cased "System" global name, which
+        # doesn't have any corresponding interfaces.
+        self._globalScope.globalNames.add("System")
+        self._globalScope.globalNameMapping["System"].add("BackstagePass")
         self._installBuiltins(self._globalScope)
         self._productions = []
 
@@ -5548,6 +5777,7 @@ class Parser(Tokenizer):
     # Builtin IDL defined by WebIDL
     _builtins = """
         typedef unsigned long long DOMTimeStamp;
+        typedef (ArrayBufferView or ArrayBuffer) BufferSource;
     """
 
 def main():
diff --git a/components/script/dom/bindings/codegen/parser/external.patch b/components/script/dom/bindings/codegen/parser/external.patch
index 9464511a9d0..964a6d8774a 100644
--- a/components/script/dom/bindings/codegen/parser/external.patch
+++ b/components/script/dom/bindings/codegen/parser/external.patch
@@ -1,16 +1,18 @@
 --- WebIDL.py
 +++ WebIDL.py
-@@ -450,44 +450,8 @@ class IDLIdentifierPlaceholder(IDLObjectWithIdentifier):
+@@ -505,46 +505,8 @@ class IDLExposureMixins():
  
- class IDLExternalInterface(IDLObjectWithIdentifier):
+ class IDLExternalInterface(IDLObjectWithIdentifier, IDLExposureMixins):
      def __init__(self, location, parentScope, identifier):
 -        assert isinstance(identifier, IDLUnresolvedIdentifier)
 -        assert isinstance(parentScope, IDLScope)
 -        self.parent = None
 -        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+-        IDLExposureMixins.__init__(self, location)
 -        IDLObjectWithIdentifier.resolve(self, parentScope)
 -
 -    def finish(self, scope):
+-        IDLExposureMixins.finish(self, scope)
 -        pass
 -
 -    def validate(self):
diff --git a/components/script/dom/bindings/codegen/parser/module.patch b/components/script/dom/bindings/codegen/parser/module.patch
index f2ed1aff944..aaec7c61b7e 100644
--- a/components/script/dom/bindings/codegen/parser/module.patch
+++ b/components/script/dom/bindings/codegen/parser/module.patch
@@ -1,15 +1,16 @@
 --- WebIDL.py
 +++ WebIDL.py
-@@ -1422,6 +1422,9 @@ class IDLDictionary(IDLObjectWithScope):
+@@ -1506,6 +1506,9 @@ class IDLDictionary(IDLObjectWithScope):
                                    self.identifier.name,
                                    [member.location] + locations)
-
+ 
 +    def module(self):
 +        return self.location.filename().split('/')[-1].split('.webidl')[0] + 'Binding'
 +
      def addExtendedAttributes(self, attrs):
          assert len(attrs) == 0
-@@ -3398,6 +3398,9 @@ class IDLCallbackType(IDLType, IDLObjectWithScope):
+ 
+@@ -3574,6 +3577,9 @@ class IDLCallbackType(IDLType, IDLObjectWithScope):
          self._treatNonCallableAsNull = False
          self._treatNonObjectAsNull = False
  
diff --git a/components/script/dom/bindings/conversions.rs b/components/script/dom/bindings/conversions.rs
index a8a8775be40..9aa6331f2ed 100644
--- a/components/script/dom/bindings/conversions.rs
+++ b/components/script/dom/bindings/conversions.rs
@@ -19,6 +19,7 @@
 //! | float                   | `f32`                            |
 //! | double                  | `f64`                            |
 //! | DOMString               | `DOMString`                      |
+//! | USVString               | `USVString`                      |
 //! | ByteString              | `ByteString`                     |
 //! | object                  | `*mut JSObject`                  |
 //! | interface types         | `JSRef<T>`      | `Temporary<T>` |
@@ -31,7 +32,7 @@
 
 use dom::bindings::codegen::PrototypeList;
 use dom::bindings::js::{JSRef, Root, Unrooted};
-use dom::bindings::str::ByteString;
+use dom::bindings::str::{ByteString, USVString};
 use dom::bindings::utils::{Reflectable, Reflector, DOMClass};
 use util::str::DOMString;
 
@@ -306,6 +307,7 @@ pub fn jsstring_to_str(cx: *mut JSContext, s: *mut JSString) -> DOMString {
     unsafe {
         let mut length = 0;
         let chars = JS_GetStringCharsAndLength(cx, s, &mut length);
+        assert!(!chars.is_null());
         let char_vec = slice::from_raw_parts(chars, length as usize);
         String::from_utf16(char_vec).unwrap()
     }
@@ -339,6 +341,32 @@ impl FromJSValConvertible for DOMString {
     }
 }
 
+impl ToJSValConvertible for USVString {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        self.0.to_jsval(cx)
+    }
+}
+
+impl FromJSValConvertible for USVString {
+    type Config = ();
+    fn from_jsval(cx: *mut JSContext, value: JSVal, _: ())
+                  -> Result<USVString, ()> {
+        let jsstr = unsafe { JS_ValueToString(cx, value) };
+        if jsstr.is_null() {
+            debug!("JS_ValueToString failed");
+            Err(())
+        } else {
+            unsafe {
+                let mut length = 0;
+                let chars = JS_GetStringCharsAndLength(cx, jsstr, &mut length);
+                assert!(!chars.is_null());
+                let char_vec = slice::from_raw_parts(chars, length as usize);
+                Ok(USVString(String::from_utf16_lossy(char_vec)))
+            }
+        }
+    }
+}
+
 impl ToJSValConvertible for ByteString {
     fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
         unsafe {
diff --git a/components/script/dom/bindings/str.rs b/components/script/dom/bindings/str.rs
index 3c47826b023..38e7d898e97 100644
--- a/components/script/dom/bindings/str.rs
+++ b/components/script/dom/bindings/str.rs
@@ -157,3 +157,7 @@ impl FromStr for ByteString {
         Ok(ByteString::new(s.to_owned().into_bytes()))
     }
 }
+
+/// A string that is constructed from a UCS-2 buffer by replacing invalid code
+/// points with the replacement character.
+pub struct USVString(pub String);
diff --git a/components/script/dom/location.rs b/components/script/dom/location.rs
index 13cc1a05c65..4f02a7952b7 100644
--- a/components/script/dom/location.rs
+++ b/components/script/dom/location.rs
@@ -6,6 +6,7 @@ use dom::bindings::codegen::Bindings::LocationBinding;
 use dom::bindings::codegen::Bindings::LocationBinding::LocationMethods;
 use dom::bindings::global::GlobalRef;
 use dom::bindings::js::{JS, JSRef, Temporary};
+use dom::bindings::str::USVString;
 use dom::bindings::utils::{Reflector, reflect_dom_object};
 use dom::urlhelper::UrlHelper;
 use dom::window::Window;
@@ -41,19 +42,19 @@ impl<'a> LocationMethods for JSRef<'a, Location> {
         self.window.root().r().load_url(url);
     }
 
-    fn Href(self) -> DOMString {
+    fn Href(self) -> USVString {
         UrlHelper::Href(&self.get_url())
     }
 
     fn Stringify(self) -> DOMString {
-        self.Href()
+        self.Href().0
     }
 
-    fn Search(self) -> DOMString {
+    fn Search(self) -> USVString {
         UrlHelper::Search(&self.get_url())
     }
 
-    fn Hash(self) -> DOMString {
+    fn Hash(self) -> USVString {
         UrlHelper::Hash(&self.get_url())
     }
 }
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index c6810483a88..5a88db06fdc 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -14,7 +14,7 @@ use dom::bindings::codegen::UnionTypes::HTMLElementOrLong;
 use dom::bindings::codegen::UnionTypes::HTMLElementOrLong::eLong;
 use dom::bindings::global::GlobalField;
 use dom::bindings::js::{JSRef, Temporary};
-use dom::bindings::str::ByteString;
+use dom::bindings::str::{ByteString, USVString};
 use dom::bindings::utils::{Reflector, Reflectable};
 use dom::blob::Blob;
 use util::str::DOMString;
@@ -55,6 +55,8 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn SetDoubleAttribute(self, _: f64) {}
     fn StringAttribute(self) -> DOMString { "".to_owned() }
     fn SetStringAttribute(self, _: DOMString) {}
+    fn UsvstringAttribute(self) -> USVString { USVString("".to_owned()) }
+    fn SetUsvstringAttribute(self, _: USVString) {}
     fn ByteStringAttribute(self) -> ByteString { ByteString::new(vec!()) }
     fn SetByteStringAttribute(self, _: ByteString) {}
     fn EnumAttribute(self) -> TestEnum { _empty }
@@ -98,6 +100,8 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn SetByteStringAttributeNullable(self, _: Option<ByteString>) {}
     fn GetStringAttributeNullable(self) -> Option<DOMString> { Some("".to_owned()) }
     fn SetStringAttributeNullable(self, _: Option<DOMString>) {}
+    fn GetUsvstringAttributeNullable(self) -> Option<USVString> { Some(USVString("".to_owned())) }
+    fn SetUsvstringAttributeNullable(self, _: Option<USVString>) {}
     fn SetBinaryRenamedAttribute(self, _: DOMString) {}
     fn BinaryRenamedAttribute(self) -> DOMString { "".to_owned() }
     fn GetEnumAttributeNullable(self) -> Option<TestEnum> { Some(_empty) }
@@ -124,6 +128,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn ReceiveFloat(self) -> f32 { 0. }
     fn ReceiveDouble(self) -> f64 { 0. }
     fn ReceiveString(self) -> DOMString { "".to_owned() }
+    fn ReceiveUsvstring(self) -> USVString { USVString("".to_owned()) }
     fn ReceiveByteString(self) -> ByteString { ByteString::new(vec!()) }
     fn ReceiveEnum(self) -> TestEnum { _empty }
     fn ReceiveInterface(self) -> Temporary<Blob> {
@@ -146,6 +151,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn ReceiveNullableFloat(self) -> Option<f32> { Some(0.) }
     fn ReceiveNullableDouble(self) -> Option<f64> { Some(0.) }
     fn ReceiveNullableString(self) -> Option<DOMString> { Some("".to_owned()) }
+    fn ReceiveNullableUsvstring(self) -> Option<USVString> { Some(USVString("".to_owned())) }
     fn ReceiveNullableByteString(self) -> Option<ByteString> { Some(ByteString::new(vec!())) }
     fn ReceiveNullableEnum(self) -> Option<TestEnum> { Some(_empty) }
     fn ReceiveNullableInterface(self) -> Option<Temporary<Blob>> {
@@ -167,6 +173,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassFloat(self, _: f32) {}
     fn PassDouble(self, _: f64) {}
     fn PassString(self, _: DOMString) {}
+    fn PassUsvstring(self, _: USVString) {}
     fn PassByteString(self, _: ByteString) {}
     fn PassEnum(self, _: TestEnum) {}
     fn PassInterface(self, _: JSRef<Blob>) {}
@@ -189,6 +196,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassNullableFloat(self, _: Option<f32>) {}
     fn PassNullableDouble(self, _: Option<f64>) {}
     fn PassNullableString(self, _: Option<DOMString>) {}
+    fn PassNullableUsvstring(self, _: Option<USVString>) {}
     fn PassNullableByteString(self, _: Option<ByteString>) {}
     // fn PassNullableEnum(self, _: Option<TestEnum>) {}
     fn PassNullableInterface(self, _: Option<JSRef<Blob>>) {}
@@ -209,6 +217,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassOptionalFloat(self, _: Option<f32>) {}
     fn PassOptionalDouble(self, _: Option<f64>) {}
     fn PassOptionalString(self, _: Option<DOMString>) {}
+    fn PassOptionalUsvstring(self, _: Option<USVString>) {}
     fn PassOptionalByteString(self, _: Option<ByteString>) {}
     fn PassOptionalEnum(self, _: Option<TestEnum>) {}
     fn PassOptionalInterface(self, _: Option<JSRef<Blob>>) {}
@@ -230,6 +239,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassOptionalNullableFloat(self, _: Option<Option<f32>>) {}
     fn PassOptionalNullableDouble(self, _: Option<Option<f64>>) {}
     fn PassOptionalNullableString(self, _: Option<Option<DOMString>>) {}
+    fn PassOptionalNullableUsvstring(self, _: Option<Option<USVString>>) {}
     fn PassOptionalNullableByteString(self, _: Option<Option<ByteString>>) {}
     // fn PassOptionalNullableEnum(self, _: Option<Option<TestEnum>>) {}
     fn PassOptionalNullableInterface(self, _: Option<Option<JSRef<Blob>>>) {}
@@ -248,6 +258,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassOptionalLongLongWithDefault(self, _: i64) {}
     fn PassOptionalUnsignedLongLongWithDefault(self, _: u64) {}
     fn PassOptionalStringWithDefault(self, _: DOMString) {}
+    fn PassOptionalUsvstringWithDefault(self, _: USVString) {}
     fn PassOptionalEnumWithDefault(self, _: TestEnum) {}
 
     fn PassOptionalNullableBooleanWithDefault(self, _: Option<bool>) {}
@@ -262,6 +273,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     // fn PassOptionalNullableFloatWithDefault(self, _: Option<f32>) {}
     // fn PassOptionalNullableDoubleWithDefault(self, _: Option<f64>) {}
     fn PassOptionalNullableStringWithDefault(self, _: Option<DOMString>) {}
+    fn PassOptionalNullableUsvstringWithDefault(self, _: Option<USVString>) {}
     fn PassOptionalNullableByteStringWithDefault(self, _: Option<ByteString>) {}
     // fn PassOptionalNullableEnumWithDefault(self, _: Option<TestEnum>) {}
     fn PassOptionalNullableInterfaceWithDefault(self, _: Option<JSRef<Blob>>) {}
@@ -283,6 +295,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     // fn PassOptionalNullableFloatWithNonNullDefault(self, _: Option<f32>) {}
     // fn PassOptionalNullableDoubleWithNonNullDefault(self, _: Option<f64>) {}
     fn PassOptionalNullableStringWithNonNullDefault(self, _: Option<DOMString>) {}
+    fn PassOptionalNullableUsvstringWithNonNullDefault(self, _: Option<USVString>) {}
     // fn PassOptionalNullableEnumWithNonNullDefault(self, _: Option<TestEnum>) {}
 
     fn PassVariadicBoolean(self, _: Vec<bool>) {}
@@ -297,6 +310,7 @@ impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
     fn PassVariadicFloat(self, _: Vec<f32>) {}
     fn PassVariadicDouble(self, _: Vec<f64>) {}
     fn PassVariadicString(self, _: Vec<DOMString>) {}
+    fn PassVariadicUsvstring(self, _: Vec<USVString>) {}
     fn PassVariadicByteString(self, _: Vec<ByteString>) {}
     fn PassVariadicEnum(self, _: Vec<TestEnum>) {}
     // fn PassVariadicInterface(self, _: Vec<JSRef<Blob>>) {}
diff --git a/components/script/dom/urlhelper.rs b/components/script/dom/urlhelper.rs
index 66eec322176..c83e65c98b2 100644
--- a/components/script/dom/urlhelper.rs
+++ b/components/script/dom/urlhelper.rs
@@ -2,7 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use util::str::DOMString;
+use dom::bindings::str::USVString;
+
 use url::Url;
 
 use std::borrow::ToOwned;
@@ -10,24 +11,24 @@ use std::borrow::ToOwned;
 pub struct UrlHelper;
 
 impl UrlHelper {
-    pub fn Href(url: &Url) -> DOMString {
-        url.serialize()
+    pub fn Href(url: &Url) -> USVString {
+        USVString(url.serialize())
     }
 
-    pub fn Search(url: &Url) -> DOMString {
-        match url.query {
+    pub fn Search(url: &Url) -> USVString {
+        USVString(match url.query {
             None => "".to_owned(),
             Some(ref query) if query.as_slice() == "" => "".to_owned(),
             Some(ref query) => format!("?{}", query)
-        }
+        })
     }
 
-    pub fn Hash(url: &Url) -> DOMString {
-        match url.fragment {
+    pub fn Hash(url: &Url) -> USVString {
+        USVString(match url.fragment {
             None => "".to_owned(),
             Some(ref hash) if hash.as_slice() == "" => "".to_owned(),
             Some(ref hash) => format!("#{}", hash)
-        }
+        })
     }
 
     /// https://html.spec.whatwg.org/multipage/browsers.html#same-origin
diff --git a/components/script/dom/webidls/TestBinding.webidl b/components/script/dom/webidls/TestBinding.webidl
index 1546152acf4..4c98746a9f1 100644
--- a/components/script/dom/webidls/TestBinding.webidl
+++ b/components/script/dom/webidls/TestBinding.webidl
@@ -17,6 +17,7 @@ dictionary TestDictionary {
   float floatValue;
   double doubleValue;
   DOMString stringValue;
+  USVString usvstringValue;
   TestEnum enumValue;
   Blob interfaceValue;
   any anyValue;
@@ -35,6 +36,7 @@ dictionary TestDictionaryDefaults {
   // float floatValue = 7.0;
   // double doubleValue = 7.0;
   DOMString stringValue = "foo";
+  USVString usvstringValue = "foo";
   TestEnum enumValue = "bar";
   any anyValue = null;
 
@@ -50,6 +52,7 @@ dictionary TestDictionaryDefaults {
   // float? nullableFloatValue = 7.0;
   // double? nullableDoubleValue = 7.0;
   DOMString? nullableStringValue = "foo";
+  USVString? nullableUsvstringValue = "foo";
   // TestEnum? nullableEnumValue = "bar";
 };
 
@@ -66,6 +69,7 @@ interface TestBinding {
            attribute float floatAttribute;
            attribute double doubleAttribute;
            attribute DOMString stringAttribute;
+           attribute USVString usvstringAttribute;
            attribute ByteString byteStringAttribute;
            attribute TestEnum enumAttribute;
            attribute Blob interfaceAttribute;
@@ -86,6 +90,7 @@ interface TestBinding {
            attribute float? floatAttributeNullable;
            attribute double? doubleAttributeNullable;
            attribute DOMString? stringAttributeNullable;
+           attribute USVString? usvstringAttributeNullable;
            attribute ByteString? byteStringAttributeNullable;
   readonly attribute TestEnum? enumAttributeNullable;
            attribute Blob? interfaceAttributeNullable;
@@ -107,6 +112,7 @@ interface TestBinding {
   float receiveFloat();
   double receiveDouble();
   DOMString receiveString();
+  USVString receiveUsvstring();
   ByteString receiveByteString();
   TestEnum receiveEnum();
   Blob receiveInterface();
@@ -126,6 +132,7 @@ interface TestBinding {
   float? receiveNullableFloat();
   double? receiveNullableDouble();
   DOMString? receiveNullableString();
+  USVString? receiveNullableUsvstring();
   ByteString? receiveNullableByteString();
   TestEnum? receiveNullableEnum();
   Blob? receiveNullableInterface();
@@ -144,6 +151,7 @@ interface TestBinding {
   void passFloat(float arg);
   void passDouble(double arg);
   void passString(DOMString arg);
+  void passUsvstring(USVString arg);
   void passByteString(ByteString arg);
   void passEnum(TestEnum arg);
   void passInterface(Blob arg);
@@ -166,6 +174,7 @@ interface TestBinding {
   void passNullableFloat(float? arg);
   void passNullableDouble(double? arg);
   void passNullableString(DOMString? arg);
+  void passNullableUsvstring(USVString? arg);
   void passNullableByteString(ByteString? arg);
   // void passNullableEnum(TestEnum? arg);
   void passNullableInterface(Blob? arg);
@@ -186,6 +195,7 @@ interface TestBinding {
   void passOptionalFloat(optional float arg);
   void passOptionalDouble(optional double arg);
   void passOptionalString(optional DOMString arg);
+  void passOptionalUsvstring(optional USVString arg);
   void passOptionalByteString(optional ByteString arg);
   void passOptionalEnum(optional TestEnum arg);
   void passOptionalInterface(optional Blob arg);
@@ -207,6 +217,7 @@ interface TestBinding {
   void passOptionalNullableFloat(optional float? arg);
   void passOptionalNullableDouble(optional double? arg);
   void passOptionalNullableString(optional DOMString? arg);
+  void passOptionalNullableUsvstring(optional USVString? arg);
   void passOptionalNullableByteString(optional ByteString? arg);
   // void passOptionalNullableEnum(optional TestEnum? arg);
   void passOptionalNullableInterface(optional Blob? arg);
@@ -225,6 +236,7 @@ interface TestBinding {
   void passOptionalLongLongWithDefault(optional long long arg = -12);
   void passOptionalUnsignedLongLongWithDefault(optional unsigned long long arg = 17);
   void passOptionalStringWithDefault(optional DOMString arg = "x");
+  void passOptionalUsvstringWithDefault(optional USVString arg = "x");
   void passOptionalEnumWithDefault(optional TestEnum arg = "foo");
   // void passOptionalUnionWithDefault(optional (HTMLElement or long) arg = 9);
   // void passOptionalUnion2WithDefault(optional(Event or DOMString)? data = "foo");
@@ -239,6 +251,7 @@ interface TestBinding {
   void passOptionalNullableLongLongWithDefault(optional long long? arg = null);
   void passOptionalNullableUnsignedLongLongWithDefault(optional unsigned long long? arg = null);
   void passOptionalNullableStringWithDefault(optional DOMString? arg = null);
+  void passOptionalNullableUsvstringWithDefault(optional USVString? arg = null);
   void passOptionalNullableByteStringWithDefault(optional ByteString? arg = null);
   // void passOptionalNullableEnumWithDefault(optional TestEnum? arg = null);
   void passOptionalNullableInterfaceWithDefault(optional Blob? arg = null);
@@ -260,6 +273,7 @@ interface TestBinding {
   // void passOptionalNullableFloatWithNonNullDefault(optional float? arg = 0.0);
   // void passOptionalNullableDoubleWithNonNullDefault(optional double? arg = 0.0);
   void passOptionalNullableStringWithNonNullDefault(optional DOMString? arg = "x");
+  void passOptionalNullableUsvstringWithNonNullDefault(optional USVString? arg = "x");
   // void passOptionalNullableEnumWithNonNullDefault(optional TestEnum? arg = "foo");
   // void passOptionalNullableUnionWithNonNullDefault(optional (HTMLElement or long)? arg = 7);
   // void passOptionalNullableUnion2WithNonNullDefault(optional (Event or DOMString)? data = "foo");
@@ -276,6 +290,7 @@ interface TestBinding {
   void passVariadicFloat(float... args);
   void passVariadicDouble(double... args);
   void passVariadicString(DOMString... args);
+  void passVariadicUsvstring(USVString... args);
   void passVariadicByteString(ByteString... args);
   void passVariadicEnum(TestEnum... args);
   // void passVariadicInterface(Blob... args);
diff --git a/components/script/dom/webidls/TreeWalker.webidl b/components/script/dom/webidls/TreeWalker.webidl
index cdd1f2d8c4c..42617f3a0bb 100644
--- a/components/script/dom/webidls/TreeWalker.webidl
+++ b/components/script/dom/webidls/TreeWalker.webidl
@@ -8,7 +8,7 @@
  */
 
 interface TreeWalker {
-  [SameObject,Constant]
+  [SameObject]
   readonly attribute Node root;
   [Constant]
   readonly attribute unsigned long whatToShow;
diff --git a/components/script/dom/webidls/URLUtils.webidl b/components/script/dom/webidls/URLUtils.webidl
index 4abb2048917..bdeca5aeabf 100644
--- a/components/script/dom/webidls/URLUtils.webidl
+++ b/components/script/dom/webidls/URLUtils.webidl
@@ -6,21 +6,21 @@
 // http://url.spec.whatwg.org/#urlutils
 [NoInterfaceObject]
 interface URLUtils {
-  //stringifier attribute ScalarValueString href;
-  readonly attribute DOMString href;
-  //readonly attribute ScalarValueString origin;
-  //         attribute ScalarValueString protocol;
-  //         attribute ScalarValueString username;
-  //         attribute ScalarValueString password;
-  //         attribute ScalarValueString host;
-  //         attribute ScalarValueString hostname;
-  //         attribute ScalarValueString port;
-  //         attribute ScalarValueString pathname;
-  //         attribute ScalarValueString search;
-  readonly attribute DOMString search;
+  //stringifier attribute USVString href;
+  readonly attribute USVString href;
+  //readonly attribute USVString origin;
+  //         attribute USVString protocol;
+  //         attribute USVString username;
+  //         attribute USVString password;
+  //         attribute USVString host;
+  //         attribute USVString hostname;
+  //         attribute USVString port;
+  //         attribute USVString pathname;
+  //         attribute USVString search;
+  readonly attribute USVString search;
   //         attribute URLSearchParams searchParams;
-  //         attribute ScalarValueString hash;
-  readonly attribute DOMString hash;
+  //         attribute USVString hash;
+  readonly attribute USVString hash;
 
   // This is only doing as well as gecko right now, bug 824857 is on file for
   // adding attribute stringifier support.
diff --git a/components/script/dom/webidls/URLUtilsReadOnly.webidl b/components/script/dom/webidls/URLUtilsReadOnly.webidl
index 8518019a6c1..3b152ad8036 100644
--- a/components/script/dom/webidls/URLUtilsReadOnly.webidl
+++ b/components/script/dom/webidls/URLUtilsReadOnly.webidl
@@ -7,17 +7,15 @@
 [NoInterfaceObject/*,
  Exposed=(Window,Worker)*/]
 interface URLUtilsReadOnly {
-  //stringifier readonly attribute ScalarValueString href;
-  readonly attribute DOMString href;
-  //readonly attribute ScalarValueString origin;
+  //stringifier readonly attribute USVString href;
+  readonly attribute USVString href;
+  //readonly attribute USVString origin;
 
-  //readonly attribute ScalarValueString protocol;
-  //readonly attribute ScalarValueString host;
-  //readonly attribute ScalarValueString hostname;
-  //readonly attribute ScalarValueString port;
-  //readonly attribute ScalarValueString pathname;
-  //readonly attribute ScalarValueString search;
-  readonly attribute DOMString search;
-  //readonly attribute ScalarValueString hash;
-  readonly attribute DOMString hash;
+  //readonly attribute USVString protocol;
+  //readonly attribute USVString host;
+  //readonly attribute USVString hostname;
+  //readonly attribute USVString port;
+  //readonly attribute USVString pathname;
+  readonly attribute USVString search;
+  readonly attribute USVString hash;
 };
diff --git a/components/script/dom/workerlocation.rs b/components/script/dom/workerlocation.rs
index 787552c84a0..1f176e2c7d9 100644
--- a/components/script/dom/workerlocation.rs
+++ b/components/script/dom/workerlocation.rs
@@ -6,12 +6,11 @@ use dom::bindings::codegen::Bindings::WorkerLocationBinding;
 use dom::bindings::codegen::Bindings::WorkerLocationBinding::WorkerLocationMethods;
 use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::global::GlobalRef;
+use dom::bindings::str::USVString;
 use dom::bindings::utils::{Reflector, reflect_dom_object};
 use dom::urlhelper::UrlHelper;
 use dom::workerglobalscope::WorkerGlobalScope;
 
-use util::str::DOMString;
-
 use url::Url;
 
 #[dom_struct]
@@ -36,15 +35,15 @@ impl WorkerLocation {
 }
 
 impl<'a> WorkerLocationMethods for JSRef<'a, WorkerLocation> {
-    fn Href(self) -> DOMString {
+    fn Href(self) -> USVString {
         UrlHelper::Href(&self.url)
     }
 
-    fn Search(self) -> DOMString {
+    fn Search(self) -> USVString {
         UrlHelper::Search(&self.url)
     }
 
-    fn Hash(self) -> DOMString {
+    fn Hash(self) -> USVString {
         UrlHelper::Hash(&self.url)
     }
 }