[Editing][DOM][CodeHealth] Make Node::isContentEditable and Node::isRichEditable global functions.

third_party/WebKit/Source/core/editing/SelectionController.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)
  * Copyright (C) 2015 Google 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
@@ skipping 565 matching lines @@
 }
 
 bool SelectionController::handleGestureLongPress(const PlatformGestureEvent& gestureEvent, const HitTestResult& hitTestResult)
 {
     if (!selection().isAvailable())
         return false;
     if (hitTestResult.isLiveLink())
         return false;
 
     Node* innerNode = hitTestResult.innerNode();
-    bool innerNodeIsSelectable = innerNode && (innerNode->isContentEditable() || innerNode->canStartSelection());
+    bool innerNodeIsSelectable = innerNode && (isContentEditable(*innerNode) || innerNode->canStartSelection());
     if (!innerNodeIsSelectable)
         return false;
 
     selectClosestWordFromHitTestResult(hitTestResult, AppendTrailingWhitespace::DontAppend, SelectInputEventType::Touch);
     if (!selection().isAvailable()) {
         // "editing/selection/longpress-selection-in-iframe-removed-crash.html"
         // reach here.
         return false;
     }
     return selection().isRange();
@@ skipping 78 matching lines @@
     return event.event().altKey() && event.isOverLink();
 }
 
 bool isExtendingSelection(const MouseEventWithHitTestResults& event)
 {
     bool isMouseDownOnLinkOrImage = event.isOverLink() || event.hitTestResult().image();
     return event.event().shiftKey() && !isMouseDownOnLinkOrImage;
 }
 
 } // namespace blink