Auto merge of #6150 - servo:smupgrade3, r=mbrubeck

Upgrade to Spidermonkey 39

> Here it is.
> 
> ~~There's two major things that are unfinished here:~~
> - ~~Dealing with the unroot_must_root lint. I'm not sure about the value of this lint with the new rooting API.~~ Done.
> - ~~Updating the Cargo.locks to point to the new SM and SM binding.~~ Done.
> 
> I also included my fixes for the rust update, but these will disappear in a rebase. A rust update is necessary to support calling `Drop` on `Heap<T>` correctly when `Heap<T>` is inside a `Rc<T>`. Otherwise `&self` points to the wrong location.
> 
> Incremental GC is disabled here. I'm not sure how to deal with the incremental barriers so that's left for later.
> 
> Generational GC works. SM doesn't work without it.
> 
> The biggest change here is to the rooting API. `Root` was made movable, and `Temporary` and `JSRef` was removed. Movable `Root`s means there's no need for `Temporary`, and `JSRef`s aren't needed generally since it can be assumed that being able to obtain a reference to a dom object means it's already rooted. References have their lifetime bound to the Roots that provided them. DOM objects that haven't passed through `reflect_dom_object` don't need to be rooted, and DOM objects that have passed through `reflect_dom_object` can't be obtained without being rooted through `native_from_reflector_jsmanaged` or `JS::<T>::root()`.
> 
> Support for `Heap<T>` ended up messier than I expected. It's split into two commits, but only because it's a bit difficult to fold them together. Supporting `Heap<T>` properly requires that that `Heap::<T>::set()` be called on something that won't move. I removed the Copy and Clone trait from `Heap<T>` so `Cell` can't hold `Heap<T>` - only `UnsafeCell` can hold it.
> 
> `CallbackObject` is a bit tricky - I moved all callbacks into `Rc<T>` in order to make sure that the pointer inside to a `*mut JSObject` doesn't move. This is necessary for supporting `Heap<T>`.
> 
> `RootedCollectionSet` is very general purpose now. Anything with `JSTraceable` can be rooted by `RootedCollectionSet`/`RootedTraceable`. Right now, `RootedTraceable` is only used to hold down dom objects before they're fully attached to their reflector. I had to make a custom mechanism to dispatch the trace call - couldn't figure out how to get trait objects working for this case.
> 
> This has been tested with the following zeal settings:
> 
> GC after every allocation
> JS_GC_ZEAL=2,1
> 
> GC after every 100 allocations (important for catching use-after-free bugs)
> JS_GC_ZEAL=2,100
> 
> Verify pre barriers
> JS_GC_ZEAL=4,1
> 
> Verify post barriers
> JS_GC_ZEAL=11,1

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1 files changed, 10 insertions, 12 deletions

diff --git a/components/script/dom/htmloptgroupelement.rs b/components/script/dom/htmloptgroupelement.rs
index 15e70190ba3..76f0a3c283e 100644
--- a/components/script/dom/htmloptgroupelement.rs
+++ b/components/script/dom/htmloptgroupelement.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::HTMLOptGroupElementBinding;
 use dom::bindings::codegen::Bindings::HTMLOptGroupElementBinding::HTMLOptGroupElementMethods;
 use dom::bindings::codegen::InheritTypes::{HTMLElementCast, NodeCast};
 use dom::bindings::codegen::InheritTypes::{HTMLOptGroupElementDerived, HTMLOptionElementDerived};
-use dom::bindings::js::{JSRef, Rootable, Temporary};
+use dom::bindings::js::Root;
 use dom::document::Document;
 use dom::element::AttributeHandlers;
 use dom::eventtarget::{EventTarget, EventTargetTypeId};
@@ -35,7 +35,7 @@ impl HTMLOptGroupElementDerived for EventTarget {
 impl HTMLOptGroupElement {
     fn new_inherited(localName: DOMString,
                      prefix: Option<DOMString>,
-                     document: JSRef<Document>) -> HTMLOptGroupElement {
+                     document: &Document) -> HTMLOptGroupElement {
         HTMLOptGroupElement {
             htmlelement:
                 HTMLElement::new_inherited(HTMLElementTypeId::HTMLOptGroupElement, localName, prefix, document)
@@ -45,13 +45,13 @@ impl HTMLOptGroupElement {
     #[allow(unrooted_must_root)]
     pub fn new(localName: DOMString,
                prefix: Option<DOMString>,
-               document: JSRef<Document>) -> Temporary<HTMLOptGroupElement> {
+               document: &Document) -> Root<HTMLOptGroupElement> {
         let element = HTMLOptGroupElement::new_inherited(localName, prefix, document);
         Node::reflect_node(box element, document, HTMLOptGroupElementBinding::Wrap)
     }
 }
 
-impl<'a> HTMLOptGroupElementMethods for JSRef<'a, HTMLOptGroupElement> {
+impl<'a> HTMLOptGroupElementMethods for &'a HTMLOptGroupElement {
     // https://www.whatwg.org/html#dom-optgroup-disabled
     make_bool_getter!(Disabled);
 
@@ -59,24 +59,23 @@ impl<'a> HTMLOptGroupElementMethods for JSRef<'a, HTMLOptGroupElement> {
     make_bool_setter!(SetDisabled, "disabled");
 }
 
-impl<'a> VirtualMethods for JSRef<'a, HTMLOptGroupElement> {
+impl<'a> VirtualMethods for &'a HTMLOptGroupElement {
     fn super_type<'b>(&'b self) -> Option<&'b VirtualMethods> {
-        let htmlelement: &JSRef<HTMLElement> = HTMLElementCast::from_borrowed_ref(self);
+        let htmlelement: &&HTMLElement = HTMLElementCast::from_borrowed_ref(self);
         Some(htmlelement as &VirtualMethods)
     }
 
-    fn after_set_attr(&self, attr: JSRef<Attr>) {
+    fn after_set_attr(&self, attr: &Attr) {
         if let Some(ref s) = self.super_type() {
             s.after_set_attr(attr);
         }
 
         match attr.local_name() {
             &atom!("disabled") => {
-                let node: JSRef<Node> = NodeCast::from_ref(*self);
+                let node = NodeCast::from_ref(*self);
                 node.set_disabled_state(true);
                 node.set_enabled_state(false);
                 for child in node.children() {
-                    let child = child.root();
                     if child.r().is_htmloptionelement() {
                         child.r().set_disabled_state(true);
                         child.r().set_enabled_state(false);
@@ -87,18 +86,17 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLOptGroupElement> {
         }
     }
 
-    fn before_remove_attr(&self, attr: JSRef<Attr>) {
+    fn before_remove_attr(&self, attr: &Attr) {
         if let Some(ref s) = self.super_type() {
             s.before_remove_attr(attr);
         }
 
         match attr.local_name() {
             &atom!("disabled") => {
-                let node: JSRef<Node> = NodeCast::from_ref(*self);
+                let node = NodeCast::from_ref(*self);
                 node.set_disabled_state(false);
                 node.set_enabled_state(true);
                 for child in node.children() {
-                    let child = child.root();
                     if child.r().is_htmloptionelement() {
                         child.r().check_disabled_attribute();
                     }