AX: if <html> has an ARIA attribute, it's exposed as an AXGroup
https://bugs.webkit.org/show_bug.cgi?id=109008

Reviewed by Ryosuke Niwa.

Source/WebCore: 

If an <html> element had an ARIA attribute, it was being turned into an element
in the AX hierarchy. This was causing trouble for screen readers by inserting
an unexpected element in the navigation sequence.

Test: accessibility/html-html-element-is-ignored.html

* accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::determineAccessibilityRole):

LayoutTests: 

* accessibility/html-html-element-is-ignored-expected.txt: Added.
* accessibility/html-html-element-is-ignored.html: Added.
* platform/chromium/TestExpectations:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142014 268f45cc-cd09-0410-ab3c-d52691b4dbfc