AX: VoiceOver is no longer seeing items in poorly formed tables
https://bugs.webkit.org/show_bug.cgi?id=115837

Reviewed by Darin Adler.

Source/WebCore: 

In case the author didn't include the rows of a table as the 
direct children, a table needs to dive down its descendant chain
until the rows are found. 

I also took the opportunity to clean up a bit around what the different
meanings of table are in the accessibility classes.

Test: accessibility/poorly-formed-aria-table.html

* accessibility/AccessibilityARIAGrid.cpp:
(WebCore::AccessibilityARIAGrid::addRowDescendant):
(WebCore::AccessibilityARIAGrid::addChildren):
* accessibility/AccessibilityARIAGrid.h:
(AccessibilityARIAGrid):
* accessibility/AccessibilityARIAGridRow.cpp:
(WebCore::AccessibilityARIAGridRow::parentTable):
(WebCore):
* accessibility/AccessibilityARIAGridRow.h:
(AccessibilityARIAGridRow):
* accessibility/AccessibilityObject.h:
(WebCore::AccessibilityObject::isTable):
* accessibility/AccessibilityTable.h:
(AccessibilityTable):
(WebCore::AccessibilityTable::isTable):
(WebCore::toAccessibilityTable):
* accessibility/AccessibilityTableRow.cpp:
(WebCore::AccessibilityTableRow::parentTable):

LayoutTests: 

* accessibility/poorly-formed-aria-table-expected.txt: Added.
* accessibility/poorly-formed-aria-table.html: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149858 268f45cc-cd09-0410-ab3c-d52691b4dbfc