[ATK] Expose aria-flowto through ATK_RELATION_FLOWS_TO
https://bugs.webkit.org/show_bug.cgi?id=127291

Reviewed by Mario Sanchez Prada.

Source/WebCore:

Test: accessibility/aria-flowto.html

Expose aria-flowto through ATK_RELATION_FLOWS_TO according to
http://www.w3.org/TR/wai-aria-implementation/#mapping_state-property

* accessibility/atk/WebKitAccessibleWrapperAtk.cpp:
(setAtkRelationSetFromCoreObject):

Tools:

Implemented AccessibilityUIElement::ariaFlowToElementAtIndex method.

* DumpRenderTree/atk/AccessibilityUIElementAtk.cpp:
(AccessibilityUIElement::ariaFlowToElementAtIndex):
* WebKitTestRunner/InjectedBundle/atk/AccessibilityUIElementAtk.cpp:
(WTR::AccessibilityUIElement::ariaFlowToElementAtIndex):

LayoutTests:

Share aria-flowto.html with other ports. It passes on GTK and EFL.

* accessibility/aria-flowto-expected.txt: Renamed from LayoutTests/platform/mac/accessibility/aria-flowto-expected.txt.
* accessibility/aria-flowto.html: Renamed from LayoutTests/platform/mac/accessibility/aria-flowto.html.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162429 268f45cc-cd09-0410-ab3c-d52691b4dbfc