Workaround for 14802

Source/bindings/v8/ScriptDebugServer.cpp

 /*
  * Copyright (c) 2010-2011 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 375 matching lines @@
     ScriptState* currentCallFrameState = ScriptState::forContext(m_pausedContext);
     listener->didPause(currentCallFrameState, currentCallFrame(), ScriptValue(exception, currentCallFrameState->isolate()), breakpointIds);
 
     m_runningNestedMessageLoop = true;
     runMessageLoopOnPause(m_pausedContext);
     m_runningNestedMessageLoop = false;
 }
 
 void ScriptDebugServer::handleProgramBreak(const v8::Debug::EventDetails& eventDetails, v8::Handle<v8::Value> exception, v8::Handle<v8::Array> hitBreakpointNumbers)
 {
+    // FIXME(http://dartbug.com/14802): The check in the function above appears to be insufficient as
+    // m_pausedContext is cleared for current invocations of handleProgramBreak.
+    // Don't allow nested breaks.
+    if (isPaused())
+        return;
+
     m_pausedContext = eventDetails.GetEventContext();
     handleProgramBreak(eventDetails.GetExecutionState(), exception, hitBreakpointNumbers);
     m_pausedContext.Clear();
 }
 
 void ScriptDebugServer::v8DebugEventCallback(const v8::Debug::EventDetails& eventDetails)
 {
     ScriptDebugServer* thisPtr = toScriptDebugServer(eventDetails.GetCallbackData());
     thisPtr->handleV8DebugEvent(eventDetails);
 }
@@ skipping 227 matching lines @@
 {
     return PassOwnPtr<ScriptSourceCode>();
 }
 
 String ScriptDebugServer::preprocessEventListener(Frame*, const String& source, const String& url, const String& functionName)
 {
     return source;
 }
 
 } // namespace WebCore