[ATK] Use atk_object_notify_state_change instead of manually emitting signals
https://bugs.webkit.org/show_bug.cgi?id=122968

Patch by Anton Obzhirov <a.obzhirov@samsung.com> on 2013-10-21
Reviewed by Mario Sanchez Prada.

Refactor emitting "state-change" event to use atk_object_notify_state_change
instead of using g_signal_emit_by_name.

* accessibility/atk/AXObjectCacheAtk.cpp:
(WebCore::notifyChildrenSelectionChange):
(WebCore::AXObjectCache::postPlatformNotification):
(WebCore::AXObjectCache::frameLoadingEventPlatformNotification):
(WebCore::AXObjectCache::handleFocusedUIElementChanged):
* accessibility/atk/WebKitAccessibleWrapperAtk.cpp:
(webkitAccessibleDetach):
* editing/atk/FrameSelectionAtk.cpp:
(WebCore::maybeEmitTextFocusChange):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@157718 268f45cc-cd09-0410-ab3c-d52691b4dbfc