Fix crash on incorrectly formatted MHTML documents

Source/core/loader/DocumentLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * 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.
@@ skipping 158 matching lines @@
 
         void setRequest(const ResourceRequest&);
 
         void commitIfReady();
         void commitData(const char* bytes, size_t length);
         void setMainDocumentError(const ResourceError&);
         void clearMainResourceLoader();
         ResourceLoader* mainResourceLoader() const;
         void clearMainResourceHandle();
 
-        void createArchive();
+        bool maybeCreateArchive();
         void clearArchiveResources();
 
         void prepareSubframeArchiveLoadIfNeeded();
         void addAllArchiveResources(MHTMLArchive*);
 
         void willSendRequest(ResourceRequest&, const ResourceResponse&);
         void finishedLoading(double finishTime);
         void mainReceivedError(const ResourceError&);
         virtual void redirectReceived(Resource*, ResourceRequest&, const ResourceResponse&) OVERRIDE;
         virtual void responseReceived(Resource*, const ResourceResponse&) OVERRIDE;
@@ skipping 51 matching lines @@
         DocumentLoadTiming m_documentLoadTiming;
 
         double m_timeOfLastDataReceived;
 
         friend class ApplicationCacheHost;  // for substitute resource delivery
         OwnPtr<ApplicationCacheHost> m_applicationCacheHost;
     };
 }
 
 #endif // DocumentLoader_h