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, 10 deletions

diff --git a/components/script/dom/domparser.rs b/components/script/dom/domparser.rs
index 40c9d8f436c..a225817b985 100644
--- a/components/script/dom/domparser.rs
+++ b/components/script/dom/domparser.rs
@@ -10,7 +10,7 @@ use dom::bindings::codegen::Bindings::DOMParserBinding::SupportedType::{Text_htm
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{JS, JSRef, Rootable, Temporary};
+use dom::bindings::js::{JS, Root};
 use dom::bindings::utils::{Reflector, reflect_dom_object};
 use dom::document::{Document, DocumentHelpers, IsHTMLDocument};
 use dom::document::DocumentSource;
@@ -27,33 +27,33 @@ pub struct DOMParser {
 }
 
 impl DOMParser {
-    fn new_inherited(window: JSRef<Window>) -> DOMParser {
+    fn new_inherited(window: &Window) -> DOMParser {
         DOMParser {
             reflector_: Reflector::new(),
-            window: JS::from_rooted(window),
+            window: JS::from_ref(window),
         }
     }
 
-    pub fn new(window: JSRef<Window>) -> Temporary<DOMParser> {
+    pub fn new(window: &Window) -> Root<DOMParser> {
         reflect_dom_object(box DOMParser::new_inherited(window), GlobalRef::Window(window),
                            DOMParserBinding::Wrap)
     }
 
-    pub fn Constructor(global: GlobalRef) -> Fallible<Temporary<DOMParser>> {
+    pub fn Constructor(global: GlobalRef) -> Fallible<Root<DOMParser>> {
         Ok(DOMParser::new(global.as_window()))
     }
 }
 
-impl<'a> DOMParserMethods for JSRef<'a, DOMParser> {
+impl<'a> DOMParserMethods for &'a DOMParser {
     // https://domparsing.spec.whatwg.org/#the-domparser-interface
     fn ParseFromString(self,
                        s: DOMString,
                        ty: DOMParserBinding::SupportedType)
-                       -> Fallible<Temporary<Document>> {
+                       -> Fallible<Root<Document>> {
         let window = self.window.root();
         let url = window.r().get_url();
         let content_type = DOMParserBinding::SupportedTypeValues::strings[ty as usize].to_owned();
-        let doc = window.r().Document().root();
+        let doc = window.r().Document();
         let doc = doc.r();
         let loader = DocumentLoader::new(&*doc.loader());
         match ty {
@@ -63,10 +63,10 @@ impl<'a> DOMParserMethods for JSRef<'a, DOMParser> {
                                              Some(content_type),
                                              None,
                                              DocumentSource::FromParser,
-                                             loader).root();
+                                             loader);
                 parse_html(document.r(), s, &url, ParseContext::Owner(None));
                 document.r().set_ready_state(DocumentReadyState::Complete);
-                Ok(Temporary::from_rooted(document.r()))
+                Ok(document)
             }
             Text_xml => {
                 //FIXME: this should probably be FromParser when we actually parse the string (#3756).