DevTools: fix crash in ClientMessageLoopAdapter::run

Source/core/inspector/MainThreadDebugger.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:
  *
  *     * 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 106 matching lines @@
 void MainThreadDebugger::interruptMainThreadAndRun(PassOwnPtr<InspectorTaskRunner::Task> task)
 {
     MutexLocker locker(creationMutex());
     if (s_instance)
         s_instance->m_taskRunner->interruptAndRun(task);
 }
 
 void MainThreadDebugger::runMessageLoopOnPause(v8::Local<v8::Context> context)
 {
     LocalFrame* frame = retrieveFrameWithGlobalObjectCheck(context);
+    // Do not pause in Context of detached frame.
+    if (!frame)
+        return;
     LocalFrame* pausedFrame = frame->localFrameRoot();
     // Wait for continue or step command.
     m_clientMessageLoop->run(pausedFrame);
 }
 
 void MainThreadDebugger::quitMessageLoopOnPause()
 {
     m_clientMessageLoop->quitNow();
 }
 
 } // namespace blink