[ATK] build fails when accessibility is turned off
https://bugs.webkit.org/show_bug.cgi?id=113699

Patch by Ed Bartosh <bartosh@gmail.com> on 2013-04-04
Reviewed by Gyuyoung Kim.

* editing/atk/FrameSelectionAtk.cpp: Wrapped accessibility code in #if HAVE(ACCESSIBILITY)

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147615 268f45cc-cd09-0410-ab3c-d52691b4dbfc