Set default document urls to 'about:blank'.

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 3287 matching lines @@
 }
 
 EventTarget* Document::errorEventTarget() {
   return domWindow();
 }
 
 void Document::exceptionThrown(ErrorEvent* event) {
   MainThreadDebugger::instance()->exceptionThrown(this, event);
 }
 
+KURL Document::urlForBinding() {
+  if (!url().isNull()) {
+    return url();
+  }
+  return blankURL();
+}
+
 void Document::setURL(const KURL& url) {
   const KURL& newURL = url.isEmpty() ? blankURL() : url;
   if (newURL == m_url)
     return;
 
   m_url = newURL;
   m_accessEntryFromURL = nullptr;
   updateBaseURL();
   contextFeatures().urlDidChange(this);
 }
@@ skipping 3338 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif