Update HTMLElement.dir / Document.dir to return only known values

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 611 matching lines @@
 
     // Default on the root element is translate=yes.
     return true;
 }
 
 void HTMLElement::setTranslate(bool enable)
 {
     setAttribute(translateAttr, enable ? "yes" : "no");
 }
 
+// Returns the conforming 'dir' value associated with the state the attribute is in (in its canonical case), if any,
+// or the empty string if the attribute is in a state that has no associated keyword value or if the attribute is
+// not in a defined state (e.g. the attribute is missing and there is no missing value default).
+// http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#limited-to-only-known-values
+static inline const AtomicString& toValidDirValue(const AtomicString& value)
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, ltrValue, ("ltr", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, rtlValue, ("rtl", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, autoValue, ("auto", AtomicString::ConstructFromLiteral));
+
+    if (equalIgnoringCase(value, ltrValue))
+        return ltrValue;
+    if (equalIgnoringCase(value, rtlValue))
+        return rtlValue;
+    if (equalIgnoringCase(value, autoValue))
+        return autoValue;
+    return nullAtom;
+}
+
+const AtomicString& HTMLElement::dir()
+{
+    return toValidDirValue(fastGetAttribute(dirAttr));
+}
+
+void HTMLElement::setDir(const AtomicString& value)
+{
+    setAttribute(dirAttr, value);
+}
+
 HTMLFormElement* HTMLElement::findFormAncestor() const
 {
     return Traversal<HTMLFormElement>::firstAncestor(*this);
 }
 
 static inline bool elementAffectsDirectionality(const Node* node)
 {
     return node->isHTMLElement() && (isHTMLBDIElement(*node) || toHTMLElement(node)->hasAttribute(dirAttr));
 }
 
@@ skipping 322 matching lines @@
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(WebCore::HTMLElement*);
 
 void dumpInnerHTML(WebCore::HTMLElement* element)
 {
     printf("%s\n", element->innerHTML().ascii().data());
 }
 #endif