Move asserts for tracking global object detachment to WindowProxy.

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

Index: third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp b/third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp
index f3948344c3cb9617d6f8a42aa3dc9147bcf85006..7142508485d7912cc46af2c93f1ffb63a2f55e9c 100644
--- a/third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp
@@ -70,6 +70,10 @@ void RemoteWindowProxy::disposeContext(GlobalDetachmentBehavior behavior) {
     }
     V8DOMWrapper::clearNativeInfo(isolate(), context->Global());
     m_scriptState->detachGlobalObject();
+
+#if DCHECK_IS_ON()
+    didDetachGlobalObject();
+#endif
   }
 
   m_scriptState->disposePerContextData();
@@ -126,6 +130,10 @@ void RemoteWindowProxy::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