Add WebElement::isEditable.

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 501 matching lines @@
         if (node == this)
             break;
 
         if (node->nodeType() == TEXT_NODE)
             node = toText(node)->mergeNextSiblingNodesIfPossible();
         else
             node = NodeTraversal::nextPostOrder(*node);
     }
 }
 
-bool Node::isContentEditable(UserSelectAllTreatment treatment)
+bool Node::isContentEditable(UserSelectAllTreatment treatment) const
 {
     document().updateLayoutTreeIfNeeded();
     return hasEditableStyle(Editable, treatment);
 }
 
-bool Node::isContentRichlyEditable()
+bool Node::isContentRichlyEditable() const
 {
     document().updateLayoutTreeIfNeeded();
     return hasEditableStyle(RichlyEditable, UserSelectAllIsAlwaysNonEditable);
 }
 
 bool Node::hasEditableStyle(EditableLevel editableLevel, UserSelectAllTreatment treatment) const
 {
     if (isPseudoElement())
         return false;
 
@@ skipping 1859 matching lines @@
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
     else
         fprintf(stderr, "Cannot showNodePath for (nil)\n");
 }
 
 #endif