https://bugs.webkit.org/show_bug.cgi?id=95062

Reviewed by Martin Robinson.

Only increase and decrease reference count of the accessibility
UI element if it actually exists.

* DumpRenderTree/gtk/AccessibilityUIElementGtk.cpp:
(AccessibilityUIElement::AccessibilityUIElement):
(AccessibilityUIElement::~AccessibilityUIElement):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@130183 268f45cc-cd09-0410-ab3c-d52691b4dbfc