Make sure we never pass a null Frame to Document::canNavigate()

Source/core/frame/History.cpp

 /*
  * Copyright (C) 2007 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 87 matching lines @@
 void History::go(ExecutionContext* context, int distance)
 {
     if (!m_frame)
         return;
 
     ASSERT(isMainThread());
     Document* activeDocument = toDocument(context);
     if (!activeDocument)
         return;
 
-    if (!activeDocument->canNavigate(m_frame))
+    if (!activeDocument->canNavigate(*m_frame))
         return;
 
     m_frame->navigationScheduler().scheduleHistoryNavigation(distance);
 }
 
 KURL History::urlForState(const String& urlString)
 {
     Document* document = m_frame->document();
 
     if (urlString.isNull())
@@ skipping 12 matching lines @@
     KURL fullURL = urlForState(urlString);
     if (!fullURL.isValid() || !m_frame->document()->securityOrigin()->canRequest(fullURL)) {
         // We can safely expose the URL to JavaScript, as a) no redirection takes place: JavaScript already had this URL, b) JavaScript can only access a same-origin History object.
         exceptionState.throwSecurityError("A history state object with URL '" + fullURL.elidedString() + "' cannot be created in a document with origin '" + m_frame->document()->securityOrigin()->toString() + "'.");
         return;
     }
     m_frame->loader().updateForSameDocumentNavigation(fullURL, SameDocumentNavigationHistoryApi, data, type);
 }
 
 } // namespace WebCore