auto merge of #2101 : jdm/servo/newroot_rebase, r=Ms2ger

As described in #1764, this strategy uses the following properties:
* DOM members are `JS<T>` types. These cannot be used with being explicitly rooted, but they are required for compiler-derived trace hooks.
* Methods that take DOM type arguments receive `&[mut] JSRef<T>`. These are rooted value references that are cloneable but cannot escape.
* Methods that return DOM values use `Unrooted<T>`. These are values that may or may not be rooted elsewhere, but callers must root them in order to interact with them in any way. One unsoundness hole exists - `Unrooted` values must be rooted ASAP, or there exists the danger that JSAPI calls could be made that could cause the underlying JS value to be GCed.
* All methods are implemented on `JSRef<T>`, enforcing the requirement that all DOM values are rooted for the duration of a method call (with a few exceptions for layout-related code, which cannot root values and therefore interacts with `JS<T>` and `&T` values - this is safe under the assumption that layout code interacts with DOM nodes that are in the tree, therefore rooted, and does not run concurrently with content code)

1 files changed, 48 insertions, 25 deletions

diff --git a/src/components/script/dom/htmllinkelement.rs b/src/components/script/dom/htmllinkelement.rs
index ae47e5168a2..c620526bfa1 100644
--- a/src/components/script/dom/htmllinkelement.rs
+++ b/src/components/script/dom/htmllinkelement.rs
@@ -4,7 +4,7 @@
 
 use dom::bindings::codegen::BindingDeclarations::HTMLLinkElementBinding;
 use dom::bindings::codegen::InheritTypes::HTMLLinkElementDerived;
-use dom::bindings::js::JS;
+use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::error::ErrorResult;
 use dom::document::Document;
 use dom::element::HTMLLinkElementTypeId;
@@ -28,95 +28,118 @@ impl HTMLLinkElementDerived for EventTarget {
 }
 
 impl HTMLLinkElement {
-    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLLinkElement {
+    pub fn new_inherited(localName: DOMString, document: &JSRef<Document>) -> HTMLLinkElement {
         HTMLLinkElement {
             htmlelement: HTMLElement::new_inherited(HTMLLinkElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLLinkElement> {
-        let element = HTMLLinkElement::new_inherited(localName, document.clone());
+    pub fn new(localName: DOMString, document: &JSRef<Document>) -> Temporary<HTMLLinkElement> {
+        let element = HTMLLinkElement::new_inherited(localName, document);
         Node::reflect_node(~element, document, HTMLLinkElementBinding::Wrap)
     }
 }
 
-impl HTMLLinkElement {
-    pub fn Disabled(&self) -> bool {
+pub trait HTMLLinkElementMethods {
+    fn Disabled(&self) -> bool;
+    fn SetDisabled(&mut self, _disable: bool);
+    fn Href(&self) -> DOMString;
+    fn SetHref(&mut self, _href: DOMString) -> ErrorResult;
+    fn CrossOrigin(&self) -> DOMString;
+    fn SetCrossOrigin(&mut self, _cross_origin: DOMString) -> ErrorResult;
+    fn Rel(&self) -> DOMString;
+    fn SetRel(&mut self, _rel: DOMString) -> ErrorResult;
+    fn Media(&self) -> DOMString;
+    fn SetMedia(&mut self, _media: DOMString) -> ErrorResult;
+    fn Hreflang(&self) -> DOMString;
+    fn SetHreflang(&mut self, _href: DOMString) -> ErrorResult;
+    fn Type(&self) -> DOMString;
+    fn SetType(&mut self, _type: DOMString) -> ErrorResult;
+    fn Charset(&self) -> DOMString;
+    fn SetCharset(&mut self, _charset: DOMString) -> ErrorResult;
+    fn Rev(&self) -> DOMString;
+    fn SetRev(&mut self, _rev: DOMString) -> ErrorResult;
+    fn Target(&self) -> DOMString;
+    fn SetTarget(&mut self, _target: DOMString) -> ErrorResult;
+}
+
+impl<'a> HTMLLinkElementMethods for JSRef<'a, HTMLLinkElement> {
+    fn Disabled(&self) -> bool {
         false
     }
 
-    pub fn SetDisabled(&mut self, _disable: bool) {
+    fn SetDisabled(&mut self, _disable: bool) {
     }
 
-    pub fn Href(&self) -> DOMString {
+    fn Href(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetHref(&mut self, _href: DOMString) -> ErrorResult {
+    fn SetHref(&mut self, _href: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn CrossOrigin(&self) -> DOMString {
+    fn CrossOrigin(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetCrossOrigin(&mut self, _cross_origin: DOMString) -> ErrorResult {
+    fn SetCrossOrigin(&mut self, _cross_origin: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Rel(&self) -> DOMString {
+    fn Rel(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetRel(&mut self, _rel: DOMString) -> ErrorResult {
+    fn SetRel(&mut self, _rel: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Media(&self) -> DOMString {
+    fn Media(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetMedia(&mut self, _media: DOMString) -> ErrorResult {
+    fn SetMedia(&mut self, _media: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Hreflang(&self) -> DOMString {
+    fn Hreflang(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetHreflang(&mut self, _href: DOMString) -> ErrorResult {
+    fn SetHreflang(&mut self, _href: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Type(&self) -> DOMString {
+    fn Type(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetType(&mut self, _type: DOMString) -> ErrorResult {
+    fn SetType(&mut self, _type: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Charset(&self) -> DOMString {
+    fn Charset(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetCharset(&mut self, _charset: DOMString) -> ErrorResult {
+    fn SetCharset(&mut self, _charset: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Rev(&self) -> DOMString {
+    fn Rev(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetRev(&mut self, _rev: DOMString) -> ErrorResult {
+    fn SetRev(&mut self, _rev: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Target(&self) -> DOMString {
+    fn Target(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetTarget(&mut self, _target: DOMString) -> ErrorResult {
+    fn SetTarget(&mut self, _target: DOMString) -> ErrorResult {
         Ok(())
     }
 }