Re-land "Improve support for :read-only and :read-write pseudoclasses".

Source/core/html/HTMLElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Motorola Mobility. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 905 matching lines @@
 {
     if (event->type() == EventTypeNames::keypress && event->isKeyboardEvent()) {
         handleKeypressEvent(toKeyboardEvent(event));
         if (event->defaultHandled())
             return;
     }
 
     Element::defaultEventHandler(event);
 }
 
+bool HTMLElement::matchesReadOnlyPseudoClass() const
+{
+    return !matchesReadWritePseudoClass();
+}
+
+bool HTMLElement::matchesReadWritePseudoClass() const
+{
+    if (fastHasAttribute(contenteditableAttr)) {
+        const AtomicString& value = fastGetAttribute(contenteditableAttr);
+
+        if (value.isEmpty() || equalIgnoringCase(value, "true") || equalIgnoringCase(value, "plaintext-only"))
+            return true;
+        if (equalIgnoringCase(value, "false"))
+            return false;
+        // All other values should be treated as "inherit".
+    }
+
+    return parentElement() && parentElement()->rendererIsEditable();
+}
+
 void HTMLElement::handleKeypressEvent(KeyboardEvent* event)
 {
     if (!document().settings() || !document().settings()->spatialNavigationEnabled() || !supportsFocus())
         return;
     // if the element is a text form control (like <input type=text> or <textarea>)
     // or has contentEditable attribute on, we should enter a space or newline
     // even in spatial navigation mode instead of handling it as a "click" action.
     if (isTextFormControl() || isContentEditable())
         return;
     int charCode = event->charCode();
     if (charCode == '\r' || charCode == ' ') {
         dispatchSimulatedClick(event);
         event->setDefaultHandled();
     }
 }
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(WebCore::HTMLElement*);
 
 void dumpInnerHTML(WebCore::HTMLElement* element)
 {
     printf("%s\n", element->innerHTML().ascii().data());
 }
 #endif