bindings: Add empty checks for toV8()

Source/bindings/core/v8/WindowProxy.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 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 353 matching lines @@
         return;
 
     if (m_frame->isRemoteFrame()) {
         return;
     }
 
     ScriptState::Scope scope(m_scriptState.get());
     v8::Local<v8::Context> context = m_scriptState->context();
     LocalFrame* frame = toLocalFrame(m_frame);
     v8::Local<v8::Value> documentWrapper = toV8(frame->document(), context->Global(), context->GetIsolate());
+    if (documentWrapper.IsEmpty())
+        return;
     ASSERT(documentWrapper == m_document.newLocal(m_isolate) || m_document.isEmpty());
     if (m_document.isEmpty())
         updateDocumentWrapper(v8::Local<v8::Object>::Cast(documentWrapper));
     checkDocumentWrapper(m_document.newLocal(m_isolate), frame->document());
 
     ASSERT(documentWrapper->IsObject());
     if (!v8CallBoolean(context->Global()->ForceSet(context, v8AtomicString(m_isolate, "document"), documentWrapper, static_cast<v8::PropertyAttribute>(v8::ReadOnly | v8::DontDelete))))
         return;
 
     // We also stash a reference to the document on the inner global object so that
@@ skipping 133 matching lines @@
 
 void WindowProxy::updateSecurityOrigin(SecurityOrigin* origin)
 {
     ASSERT(m_world->isMainWorld());
     if (!isContextInitialized())
         return;
     setSecurityToken(origin);
 }
 
 } // namespace blink