Document.dir should reflect the 'dir' attribute of the root html element

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 1375 matching lines @@
         if (HTMLTitleElement* title = Traversal<HTMLTitleElement>::firstChild(*headElement))
             setTitleElement(title->text(), title);
     }
 
     if (!m_titleElement)
         updateTitle(String());
 }
 
 const AtomicString& Document::dir()
 {
-    // FIXME(crbug.com/363107): This should be the root html element, not the body.
-    if (HTMLElement* b = body())
-        return b->getAttribute(dirAttr);
+    Element* rootElement = documentElement();
+    if (isHTMLHtmlElement(rootElement)) {
+        // FIXME(crbug.com/363628): document.dir should only return known values.
+        return rootElement->getAttribute(dirAttr);
+    }
     return nullAtom;
 }
 
 void Document::setDir(const AtomicString& value)
 {
-    // FIXME(crbug.com/363107): This should be the root html element, not the body.
-    if (HTMLElement* b = body())
-        b->setAttribute(dirAttr, value);
+    Element* rootElement = documentElement();
+    if (isHTMLHtmlElement(rootElement))
+        rootElement->setAttribute(dirAttr, value);
 }
 
 PageVisibilityState Document::pageVisibilityState() const
 {
     // The visibility of the document is inherited from the visibility of the
     // page. If there is no page associated with the document, we will assume
     // that the page is hidden, as specified by the spec:
     // http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/PageVisibility/Overview.html#dom-document-hidden
     if (!m_frame || !m_frame->page())
         return PageVisibilityStateHidden;
@@ skipping 4121 matching lines @@
         (*it)->invalidateCache(attrName);
 }
 
 void Document::trace(Visitor* visitor)
 {
     Supplementable<Document>::trace(visitor);
     ContainerNode::trace(visitor);
 }
 
 } // namespace WebCore