https://bugs.webkit.org/show_bug.cgi?id=110050

Reviewed by Tim Horton.

Source/WebCore: 

If a table had hidden cells, then accessibility code was being confused in a few ways.
1) The cellForColumnAndRow method would return the wrong information since that was
   using the RenderTableSection to retrieve a cell, which did not have the same data as the AXTable
2) The way we were adding children made it impossible to determine column and row range because we 
   would skip rows that had hidden children
3) AccessibilityARIAGrid and AccessibilityTable were using different methods for cellForColumnAndRow

The fix does a few things to make things right:
1) Always add an accessibility row, even if there are no visible cells in that row.
2) Have one method for AXTable and AXARIAGrid for cellForColumnAndRow.
3) Change cellForColumnAndRow to query the accessibility children rather than the RenderTableSection in determining the row, col info.
4) cellForColumnAndRow should use unsigned values instead of int values.

Test: accessibility/table-with-hidden-head-section.html

* accessibility/AccessibilityARIAGrid.cpp:
(WebCore):
* accessibility/AccessibilityARIAGrid.h:
(AccessibilityARIAGrid):
* accessibility/AccessibilityARIAGridCell.cpp:
(WebCore::AccessibilityARIAGridCell::rowIndexRange):
(WebCore::AccessibilityARIAGridCell::columnIndexRange):
* accessibility/AccessibilityARIAGridCell.h:
(AccessibilityARIAGridCell):
* accessibility/AccessibilityTable.cpp:
(WebCore::AccessibilityTable::addChildren):
(WebCore::AccessibilityTable::cellForColumnAndRow):
* accessibility/AccessibilityTable.h:
(WebCore):
(AccessibilityTable):
* accessibility/AccessibilityTableCell.cpp:
(WebCore::AccessibilityTableCell::rowIndexRange):
(WebCore::AccessibilityTableCell::columnIndexRange):
* accessibility/AccessibilityTableCell.h:
(AccessibilityTableCell):
* accessibility/atk/WebKitAccessibleInterfaceTable.cpp:
(webkitAccessibleTableGetColumnAtIndex):
(webkitAccessibleTableGetRowAtIndex):
(webkitAccessibleTableGetColumnExtentAt):
(webkitAccessibleTableGetRowExtentAt):
(webkitAccessibleTableGetColumnHeader):
(webkitAccessibleTableGetRowHeader):
* accessibility/mac/WebAccessibilityObjectWrapperMac.mm:
(-[WebAccessibilityObjectWrapper accessibilityAttributeValue:]):
* rendering/RenderTableSection.h:
(RenderTableSection):
(WebCore::RenderTableSection::rowRendererAt):

Source/WebKit/chromium: 

* src/WebAccessibilityObject.cpp:
(WebKit::WebAccessibilityObject::cellColumnIndex):
(WebKit::WebAccessibilityObject::cellColumnSpan):
(WebKit::WebAccessibilityObject::cellRowIndex):
(WebKit::WebAccessibilityObject::cellRowSpan):

LayoutTests: 

* accessibility/table-with-hidden-head-section-expected.txt: Added.
* accessibility/table-with-hidden-head-section.html: Added.
* platform/chromium/TestExpectations:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144727 268f45cc-cd09-0410-ab3c-d52691b4dbfc