[GTK] Showing the context menu in the Web Inspector can crash the browser

[GTK] Showing the context menu in the Web Inspector can crash the browser
https://bugs.webkit.org/show_bug.cgi?id=88800

Patch by Arnaud Renevier <arno@renevier.net> on 2012-07-05
Reviewed by Carlos Garcia Campos.

Remove ContextMenuItem from its parent before appending it again to a
new parent

No new tests, behavior is unchanged.

* platform/gtk/ContextMenuGtk.cpp:
(WebCore::ContextMenu::appendItem):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121945 268f45cc-cd09-0410-ab3c-d52691b4dbfc