AX: move aria-invalid test to top level, so other platforms can use it

AX: move aria-invalid test to top level, so other platforms can use it
https://bugs.webkit.org/show_bug.cgi?id=79041

Reviewed by David Kilzer.

* accessibility/aria-invalid-expected.txt: Copied from LayoutTests/platform/mac/accessibility/aria-invalid-expected.txt.
* accessibility/aria-invalid.html: Copied from LayoutTests/platform/mac/accessibility/aria-invalid.html.
* platform/gtk/Skipped:
* platform/mac/accessibility/aria-invalid-expected.txt: Removed.
* platform/mac/accessibility/aria-invalid.html: Removed.
* platform/win/Skipped:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108373 268f45cc-cd09-0410-ab3c-d52691b4dbfc