First-cut at fixing unhandled Tap event returns in Blink.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * 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 520 matching lines @@
             newSelection.setExtent(pos);
 
         if (m_frame->selection().granularity() != CharacterGranularity) {
             granularity = m_frame->selection().granularity();
             newSelection.expandUsingGranularity(m_frame->selection().granularity());
         }
     } else {
         newSelection = expandSelectionToRespectUserSelectAll(innerNode, VisibleSelection(visiblePos));
     }
 
-    bool handled = updateSelectionForMouseDownDispatchingSelectStart(innerNode, newSelection, granularity);
-    return handled;
+    // Updating the selection is considered side-effect of the event and so it doesn't impact the handled state.
+    updateSelectionForMouseDownDispatchingSelectStart(innerNode, newSelection, granularity);
+    return false;
 }
 
 static inline bool canMouseDownStartSelect(Node* node)
 {
     if (!node || !node->renderer())
         return true;
 
     if (!node->canStartSelection())
         return false;
 
@@ skipping 3178 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore