buildAccessibilityTree() needs to be removed from individual layout tests
https://bugs.webkit.org/show_bug.cgi?id=95286

Reviewed by Chris Fleizach.

Extracted two functions to 'dump' and 'touch' the accessibility
hierarchies out of different layout tests and into a single file,
living in LayoutTests/resources/accessibility-helper.js

* resources/accessibility-helper.js: Added.
(dumpAccessibilityTree): New, based on buildAccessibilityTree()
for the cases where it was used to actually 'dump' it into the output.
(touchAccessibilityTree): Same, but for the cases where we don't
want to dump the accessibility tree, just to make sure is generated.

Updated affected layout tests to use the newly added helper functions.

* accessibility/adjacent-continuations-cause-assertion-failure.html: Updated.
* accessibility/children-changed-sends-notification.html: Ditto.
* accessibility/deleting-iframe-destroys-axcache.html: Ditto.
* accessibility/div-within-anchors-causes-crash.html: Ditto.
* accessibility/first-letter-text-transform-causes-crash.html: Ditto.
* accessibility/image-map-update-parent-crash.html: Ditto.
* accessibility/table-with-empty-thead-causes-crash.html: Ditto.
* platform/efl/accessibility/media-emits-object-replacement.html: Ditto.
* platform/gtk/accessibility/entry-and-password.html: Ditto.
* platform/gtk/accessibility/media-emits-object-replacement.html: Ditto.
* platform/gtk/accessibility/replaced-objects-in-anonymous-blocks.html: Ditto.

Updated Mac specific expectations not to print the "End of test" element.

* platform/mac-wk2/accessibility/deleting-iframe-destroys-axcache-expected.txt: Updated.
* platform/mac/accessibility/adjacent-continuations-cause-assertion-failure-expected.txt: Ditto.
* platform/mac/accessibility/deleting-iframe-destroys-axcache-expected.txt: Ditto.
* platform/mac/accessibility/div-within-anchors-causes-crash-expected.txt: Ditto.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170806 268f45cc-cd09-0410-ab3c-d52691b4dbfc