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, 11 deletions

diff --git a/components/script/dom/activation.rs b/components/script/dom/activation.rs
index dbbe4689e1b..67dc0f1b731 100644
--- a/components/script/dom/activation.rs
+++ b/components/script/dom/activation.rs
@@ -4,7 +4,6 @@
 
 use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use dom::bindings::codegen::InheritTypes::{EventCast, EventTargetCast};
-use dom::bindings::js::{JSRef, Temporary, OptionalRootable, Rootable};
 use dom::element::{Element, ActivationElementHelpers};
 use dom::event::{Event, EventHelpers, EventBubbles, EventCancelable};
 use dom::eventtarget::EventTarget;
@@ -15,7 +14,7 @@ use std::borrow::ToOwned;
 
 /// Trait for elements with defined activation behavior
 pub trait Activatable {
-    fn as_element(&self) -> Temporary<Element>;
+    fn as_element<'a>(&'a self) -> &'a Element;
 
     // Is this particular instance of the element activatable?
     fn is_instance_activatable(&self) -> bool;
@@ -27,32 +26,32 @@ pub trait Activatable {
     fn canceled_activation(&self);
 
     // https://html.spec.whatwg.org/multipage/#run-post-click-activation-steps
-    fn activation_behavior(&self, event: JSRef<Event>, target: JSRef<EventTarget>);
+    fn activation_behavior(&self, event: &Event, target: &EventTarget);
 
     // https://html.spec.whatwg.org/multipage/#implicit-submission
     fn implicit_submission(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool);
 
     // https://html.spec.whatwg.org/multipage/#run-synthetic-click-activation-steps
     fn synthetic_click_activation(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool) {
-        let element = self.as_element().root();
+        let element = self.as_element();
         // Step 1
-        if element.r().click_in_progress() {
+        if element.click_in_progress() {
             return;
         }
         // Step 2
-        element.r().set_click_in_progress(true);
+        element.set_click_in_progress(true);
         // Step 3
         self.pre_click_activation();
 
         // Step 4
         // https://html.spec.whatwg.org/multipage/#fire-a-synthetic-mouse-event
-        let win = window_from_node(element.r()).root();
-        let target: JSRef<EventTarget> = EventTargetCast::from_ref(element.r());
+        let win = window_from_node(element);
+        let target = EventTargetCast::from_ref(element);
         let mouse = MouseEvent::new(win.r(), "click".to_owned(),
                                     EventBubbles::DoesNotBubble, EventCancelable::NotCancelable, Some(win.r()), 1,
                                     0, 0, 0, 0, ctrlKey, shiftKey, altKey, metaKey,
-                                    0, None).root();
-        let event: JSRef<Event> = EventCast::from_ref(mouse.r());
+                                    0, None);
+        let event = EventCast::from_ref(mouse.r());
         event.fire(target);
 
         // Step 5
@@ -64,6 +63,6 @@ pub trait Activatable {
         }
 
         // Step 6
-        element.r().set_click_in_progress(false);
+        element.set_click_in_progress(false);
     }
 }