bindings: Add empty checks for toV8()

Source/web/InspectorOverlayImpl.cpp

 /*
  * Copyright (C) 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 363 matching lines @@
 
     const WebData& overlayPageHTMLResource = Platform::current()->loadResource("InspectorOverlayPage.html");
     RefPtr<SharedBuffer> data = SharedBuffer::create(overlayPageHTMLResource.data(), overlayPageHTMLResource.size());
     loader.load(FrameLoadRequest(0, blankURL(), SubstituteData(data, "text/html", "UTF-8", KURL(), ForceSynchronousLoad)));
     v8::Isolate* isolate = toIsolate(frame.get());
     ScriptState* scriptState = ScriptState::forMainWorld(frame.get());
     ASSERT(scriptState->contextIsValid());
     ScriptState::Scope scope(scriptState);
     v8::Local<v8::Object> global = scriptState->context()->Global();
     v8::Local<v8::Value> overlayHostObj = toV8(m_overlayHost.get(), global, isolate);
+    ASSERT(!overlayHostObj.IsEmpty());
     global->Set(v8AtomicString(isolate, "InspectorOverlayHost"), overlayHostObj);
 
 #if OS(WIN)
     evaluateInOverlay("setPlatform", "windows");
 #elif OS(MACOSX)
     evaluateInOverlay("setPlatform", "mac");
 #elif OS(POSIX)
     evaluateInOverlay("setPlatform", "linux");
 #endif
 
@@ skipping 71 matching lines @@
     if (!m_suspendCount++)
         clear();
 }
 
 void InspectorOverlayImpl::resumeUpdates()
 {
     --m_suspendCount;
 }
 
 } // namespace blink