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, 36 insertions, 19 deletions

diff --git a/src/components/script/dom/htmloptionelement.rs b/src/components/script/dom/htmloptionelement.rs
index e6a030df48c..550d352af36 100644
--- a/src/components/script/dom/htmloptionelement.rs
+++ b/src/components/script/dom/htmloptionelement.rs
@@ -4,7 +4,7 @@
 
 use dom::bindings::codegen::BindingDeclarations::HTMLOptionElementBinding;
 use dom::bindings::codegen::InheritTypes::HTMLOptionElementDerived;
-use dom::bindings::js::JS;
+use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::error::ErrorResult;
 use dom::document::Document;
 use dom::element::HTMLOptionElementTypeId;
@@ -29,72 +29,89 @@ impl HTMLOptionElementDerived for EventTarget {
 }
 
 impl HTMLOptionElement {
-    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLOptionElement {
+    pub fn new_inherited(localName: DOMString, document: &JSRef<Document>) -> HTMLOptionElement {
         HTMLOptionElement {
             htmlelement: HTMLElement::new_inherited(HTMLOptionElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLOptionElement> {
-        let element = HTMLOptionElement::new_inherited(localName, document.clone());
+    pub fn new(localName: DOMString, document: &JSRef<Document>) -> Temporary<HTMLOptionElement> {
+        let element = HTMLOptionElement::new_inherited(localName, document);
         Node::reflect_node(~element, document, HTMLOptionElementBinding::Wrap)
     }
 }
 
-impl HTMLOptionElement {
-    pub fn Disabled(&self) -> bool {
+pub trait HTMLOptionElementMethods {
+    fn Disabled(&self) -> bool;
+    fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult;
+    fn GetForm(&self) -> Option<Temporary<HTMLFormElement>>;
+    fn Label(&self) -> DOMString;
+    fn SetLabel(&mut self, _label: DOMString) -> ErrorResult;
+    fn DefaultSelected(&self) -> bool;
+    fn SetDefaultSelected(&mut self, _default_selected: bool) -> ErrorResult;
+    fn Selected(&self) -> bool;
+    fn SetSelected(&mut self, _selected: bool) -> ErrorResult;
+    fn Value(&self) -> DOMString;
+    fn SetValue(&mut self, _value: DOMString) -> ErrorResult;
+    fn Text(&self) -> DOMString;
+    fn SetText(&mut self, _text: DOMString) -> ErrorResult;
+    fn Index(&self) -> i32;
+}
+
+impl<'a> HTMLOptionElementMethods for JSRef<'a, HTMLOptionElement> {
+    fn Disabled(&self) -> bool {
         false
     }
 
-    pub fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult {
+    fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
+    fn GetForm(&self) -> Option<Temporary<HTMLFormElement>> {
         None
     }
 
-    pub fn Label(&self) -> DOMString {
+    fn Label(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetLabel(&mut self, _label: DOMString) -> ErrorResult {
+    fn SetLabel(&mut self, _label: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn DefaultSelected(&self) -> bool {
+    fn DefaultSelected(&self) -> bool {
         false
     }
 
-    pub fn SetDefaultSelected(&mut self, _default_selected: bool) -> ErrorResult {
+    fn SetDefaultSelected(&mut self, _default_selected: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Selected(&self) -> bool {
+    fn Selected(&self) -> bool {
         false
     }
 
-    pub fn SetSelected(&mut self, _selected: bool) -> ErrorResult {
+    fn SetSelected(&mut self, _selected: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Value(&self) -> DOMString {
+    fn Value(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetValue(&mut self, _value: DOMString) -> ErrorResult {
+    fn SetValue(&mut self, _value: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Text(&self) -> DOMString {
+    fn Text(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetText(&mut self, _text: DOMString) -> ErrorResult {
+    fn SetText(&mut self, _text: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Index(&self) -> i32 {
+    fn Index(&self) -> i32 {
         0
     }
 }