Make RootedVec/RootCollection #[no_move]; improve code (fixes #5737)

components/script/dom/bindings/js.rs

@@ -577,6 +577,7 @@ impl<T: Assignable<U>, U: Reflectable> TemporaryPushable<T> for Vec<JS<U>> {
 ///
 /// See also [*Exact Stack Rooting - Storing a GCPointer on the CStack*]
 /// (https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Internals/GC/Exact_Stack_Rooting).
+#[no_move]
 pub struct RootCollection {
     roots: UnsafeCell<RootedVec<*mut JSObject>>,
 }

components/script/dom/bindings/trace.rs

@@ -401,6 +401,7 @@ impl VecRootableType for *mut JSObject {
 /// A vector of items that are rooted for the lifetime
 /// of this struct
 #[allow(unrooted_must_root)]
+#[no_move]
 pub struct RootedVec<T> {
     v: Vec<T>
 }

components/script/dom/element.rs

@@ -728,7 +728,7 @@ impl<'a> AttributeHandlers for JSRef<'a, Element> {
     fn get_attributes(self, local_name: &Atom, attributes: &mut RootedVec<JS<Attr>>) {
         // FIXME(https://github.com/rust-lang/rust/issues/23338)
         let attrs = self.attrs.borrow();
-        for attr in attrs.iter().map(|attr| attr.root()) {
+        for ref attr in attrs.iter().map(|attr| attr.root()) {
             // FIXME(https://github.com/rust-lang/rust/issues/23338)
             let attr = attr.r();
             let attr_local_name = attr.local_name();

components/script/dom/htmlinputelement.rs

@@ -841,7 +841,7 @@ impl<'a> Activatable for JSRef<'a, HTMLInputElement> {
                 .find(|r| r.r().form_owner() == owner);
         }
         match submit_button {
-            Some(button) => {
+            Some(ref button) => {
                 if button.r().is_instance_activatable() {
                     button.r().synthetic_click_activation(ctrlKey, shiftKey, altKey, metaKey)
                 }

components/script/dom/htmllinkelement.rs

@@ -9,7 +9,7 @@ use dom::bindings::codegen::Bindings::HTMLLinkElementBinding::HTMLLinkElementMet
 use dom::bindings::codegen::InheritTypes::HTMLLinkElementDerived;
 use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLElementCast, NodeCast};
 use dom::bindings::js::{JS, JSRef, MutNullableHeap, Temporary};
-use dom::bindings::js::OptionalRootable;
+use dom::bindings::js::{OptionalRootable, RootedReference};
 use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
 use dom::element::{AttributeHandlers, Element};
@@ -60,9 +60,7 @@ impl HTMLLinkElement {
 
 fn get_attr(element: JSRef<Element>, local_name: &Atom) -> Option<String> {
     let elem = element.get_attribute(&ns!(""), local_name).root();
-    elem.as_ref().map(|e| {
+    elem.r().map(|e| {
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let e = e.r();
         let value = e.value();
         (**value).to_owned()
     })

components/script/dom/node.rs

@@ -298,7 +298,7 @@ impl<'a> PrivateNodeHelpers for JSRef<'a, Node> {
         }
 
         let parent = self.parent_node().root();
-        parent.as_ref().map(|parent| vtable_for(&parent.r()).child_inserted(self));
+        parent.r().map(|parent| vtable_for(&parent).child_inserted(self));
         document.r().content_and_heritage_changed(self, NodeDamage::OtherNodeDamage);
     }
 

components/script/script_task.rs

@@ -937,7 +937,7 @@ impl ScriptTask {
             self.find_iframe(doc.r(), old_subpage_id)
         }).root();
 
-        frame_element.as_ref().unwrap().r().update_subpage_id(new_subpage_id);
+        frame_element.r().unwrap().update_subpage_id(new_subpage_id);
     }
 
     /// Handles a notification that reflow completed.