Bug 1626794 - Add strong ref to document and MOZ_CAN_RUN_SCRIPT annotation to Animation::CommitStyles r=hiro

Differential Revision: https://phabricator.services.mozilla.com/D75418

dom/animation/Animation.cpp

@@ -707,10 +707,13 @@ void Animation::CommitStyles(ErrorResult& aRv) {
         "Target is not capable of having a style attribute");
   }
 
+  // Hold onto a strong reference to the doc in case the flush destroys it.
+  RefPtr<Document> doc = target.mElement->GetComposedDoc();
+
   // Flush frames before checking if the target element is rendered since the
   // result could depend on pending style changes, and IsRendered() looks at the
   // primary frame.
-  if (Document* doc = target.mElement->GetComposedDoc()) {
+  if (doc) {
     doc->FlushPendingNotifications(FlushType::Frames);
   }
   if (!target.mElement->IsRendered()) {

dom/animation/Animation.h

@@ -150,7 +150,7 @@ class Animation : public DOMEventTargetHelper,
   virtual void Reverse(ErrorResult& aRv);
 
   void Persist();
-  void CommitStyles(ErrorResult& aRv);
+  MOZ_CAN_RUN_SCRIPT void CommitStyles(ErrorResult& aRv);
 
   bool IsRunningOnCompositor() const;