binding: Changes the association among global-proxy/global/window-instance (2nd attempt).

third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 454 matching lines @@
 }
 
 void V8GCController::CollectAllGarbageForTesting(v8::Isolate* isolate) {
   for (unsigned i = 0; i < 5; i++)
     isolate->RequestGarbageCollectionForTesting(
         v8::Isolate::kFullGarbageCollection);
 }
 
 class DOMWrapperTracer : public v8::PersistentHandleVisitor {
  public:
-  explicit DOMWrapperTracer(Visitor* visitor) : visitor_(visitor) {}
+  explicit DOMWrapperTracer(Visitor* visitor) : visitor_(visitor) {
+    DCHECK(visitor_);
+  }
 
   void VisitPersistentHandle(v8::Persistent<v8::Value>* value,
                              uint16_t class_id) override {
     if (class_id != WrapperTypeInfo::kNodeClassId &&
         class_id != WrapperTypeInfo::kObjectClassId)
       return;
 
     const v8::Persistent<v8::Object>& wrapper =
         v8::Persistent<v8::Object>::Cast(*value);
 
-    if (visitor_)
-      ToWrapperTypeInfo(wrapper)->Trace(visitor_, ToScriptWrappable(wrapper));
+    if (ScriptWrappable* script_wrappable = ToScriptWrappable(wrapper))
+      ToWrapperTypeInfo(wrapper)->Trace(visitor_, script_wrappable);
   }
 
  private:
   Visitor* visitor_;
 };
 
 void V8GCController::TraceDOMWrappers(v8::Isolate* isolate, Visitor* visitor) {
   DOMWrapperTracer tracer(visitor);
   isolate->VisitHandlesWithClassIds(&tracer);
 }
@@ skipping 53 matching lines @@
   double start_time = WTF::CurrentTimeMS();
   v8::HandleScope scope(isolate);
   PendingActivityVisitor visitor(isolate, execution_context);
   ToIsolate(execution_context)->VisitHandlesWithClassIds(&visitor);
   scan_pending_activity_histogram.Count(
       static_cast<int>(WTF::CurrentTimeMS() - start_time));
   return visitor.PendingActivityFound();
 }
 
 }  // namespace blink