Move asserts for tracking global object detachment to WindowProxy.

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

Index: third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp b/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
index efad7d6a828fab92d52b9714bba693e4a4a80078..47b58f7dd7629c8ca269082aa9d2e2c26d9e5b02 100644
--- a/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
@@ -92,6 +92,10 @@ void LocalWindowProxy::disposeContext(GlobalDetachmentBehavior behavior) {
     }
     V8DOMWrapper::clearNativeInfo(isolate(), context->Global());
     m_scriptState->detachGlobalObject();
+
+#if DCHECK_IS_ON()
+    didDetachGlobalObject();
+#endif
   }
 
   m_scriptState->disposePerContextData();
@@ -187,6 +191,10 @@ void LocalWindowProxy::createContext() {
   }
   CHECK(!context.IsEmpty());
 
+#if DCHECK_IS_ON()
+  didAttachGlobalObject();
+#endif
+
   m_scriptState = ScriptState::create(context, m_world);
 
   // TODO(haraken): Currently we cannot enable the following DCHECK because