Properly suspend HTMLDocumentParser

Source/core/dom/ExecutionContext.cpp

Index: Source/core/dom/ExecutionContext.cpp
diff --git a/Source/core/dom/ExecutionContext.cpp b/Source/core/dom/ExecutionContext.cpp
index a492d250f89c2984c7df46962af86b2112483c35..c911df625051994921b358bc66500811066441b0 100644
--- a/Source/core/dom/ExecutionContext.cpp
+++ b/Source/core/dom/ExecutionContext.cpp
@@ -87,12 +87,14 @@ bool ExecutionContext::hasPendingActivity()
 
 void ExecutionContext::suspendActiveDOMObjects()
 {
+    ASSERT(!m_activeDOMObjectsAreSuspended);
     lifecycleNotifier().notifySuspendingActiveDOMObjects();
     m_activeDOMObjectsAreSuspended = true;
 }
 
 void ExecutionContext::resumeActiveDOMObjects()
 {
+    ASSERT(m_activeDOMObjectsAreSuspended);
     m_activeDOMObjectsAreSuspended = false;
     lifecycleNotifier().notifyResumingActiveDOMObjects();
 }