Source/WebCore: AX: Do not return an accessible name for an object just because it has tabindex=0

https://bugs.webkit.org/show_bug.cgi?id=126914

Reviewed by Mario Sanchez Prada.

WebKit has code to return an accessible name for any object that is "generically" focusable (ie. tabindex=0).
This behavior, which is not supported in ARIA, has caused many problems for VoiceOver. Often VoiceOver will
speak all the text underneath any type of group.

I think we need to revert this behavior and follow the ARIA spec more closely.

Test: accessibility/aria-describedby-ensures-visibility.html

* accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::visibleText):
(WebCore::AccessibilityNodeObject::title):

LayoutTests: AX: WebKit concatenates name of all toolbar buttons in the apple.com video player
https://bugs.webkit.org/show_bug.cgi?id=126914

Reviewed by Mario Sanchez Prada.

* accessibility/focusable-div-expected.txt:
* accessibility/focusable-div.html:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162576 268f45cc-cd09-0410-ab3c-d52691b4dbfc