Properly suspend HTMLDocumentParser

Source/core/dom/ExecutionContext.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2012 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 69 matching lines @@
 {
 }
 
 bool ExecutionContext::hasPendingActivity()
 {
     return lifecycleNotifier().hasPendingActivity();
 }
 
 void ExecutionContext::suspendActiveDOMObjects()
 {
+    ASSERT(!m_activeDOMObjectsAreSuspended);
     lifecycleNotifier().notifySuspendingActiveDOMObjects();
     m_activeDOMObjectsAreSuspended = true;
 }
 
 void ExecutionContext::resumeActiveDOMObjects()
 {
+    ASSERT(m_activeDOMObjectsAreSuspended);
     m_activeDOMObjectsAreSuspended = false;
     lifecycleNotifier().notifyResumingActiveDOMObjects();
 }
 
 void ExecutionContext::stopActiveDOMObjects()
 {
     m_activeDOMObjectsAreStopped = true;
     lifecycleNotifier().notifyStoppingActiveDOMObjects();
 }
 
@@ skipping 162 matching lines @@
 void ExecutionContext::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_pendingExceptions);
     HeapSupplementable<ExecutionContext>::trace(visitor);
 #endif
     LifecycleContext<ExecutionContext>::trace(visitor);
 }
 
 } // namespace blink