Selection API: document.open() should reset Selection.

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 2712 matching lines @@
           return;
       }
     }
 
     // PlzNavigate: We should abort ongoing navigations handled by the client.
     if (m_frame->loader().hasProvisionalNavigation())
       m_frame->loader().stopAllLoaders();
   }
 
   removeAllEventListenersRecursively();
+  resetTreeScope();
+  if (m_frame)
+    m_frame->selection().clear();
   implicitOpen(ForceSynchronousParsing);
   if (ScriptableDocumentParser* parser = scriptableDocumentParser())
     parser->setWasCreatedByScript(true);
 
   if (m_frame)
     m_frame->loader().didExplicitOpen();
   if (m_loadEventProgress != LoadEventInProgress &&
       pageDismissalEventBeingDispatched() == NoDismissal)
     m_loadEventProgress = LoadEventNotRun;
 }
@@ skipping 3914 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