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, 6 insertions, 6 deletions

diff --git a/components/script/dom/domstringmap.rs b/components/script/dom/domstringmap.rs
index f48b4218aed..625d261b686 100644
--- a/components/script/dom/domstringmap.rs
+++ b/components/script/dom/domstringmap.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::DOMStringMapBinding;
 use dom::bindings::codegen::Bindings::DOMStringMapBinding::DOMStringMapMethods;
 use dom::bindings::error::ErrorResult;
 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::node::window_from_node;
 use dom::htmlelement::{HTMLElement, HTMLElementCustomAttributeHelpers};
@@ -19,22 +19,22 @@ pub struct DOMStringMap {
 }
 
 impl DOMStringMap {
-    fn new_inherited(element: JSRef<HTMLElement>) -> DOMStringMap {
+    fn new_inherited(element: &HTMLElement) -> DOMStringMap {
         DOMStringMap {
             reflector_: Reflector::new(),
-            element: JS::from_rooted(element),
+            element: JS::from_ref(element),
         }
     }
 
-    pub fn new(element: JSRef<HTMLElement>) -> Temporary<DOMStringMap> {
-        let window = window_from_node(element).root();
+    pub fn new(element: &HTMLElement) -> Root<DOMStringMap> {
+        let window = window_from_node(element);
         reflect_dom_object(box DOMStringMap::new_inherited(element),
                            GlobalRef::Window(window.r()), DOMStringMapBinding::Wrap)
     }
 }
 
 // https://html.spec.whatwg.org/#domstringmap
-impl<'a> DOMStringMapMethods for JSRef<'a, DOMStringMap> {
+impl<'a> DOMStringMapMethods for &'a DOMStringMap {
     fn NamedCreator(self, name: DOMString, value: DOMString) -> ErrorResult {
         self.NamedSetter(name, value)
     }