And we didn't notice it because context menu API tests are skipped (see https://bugs.webkit.org/show_bug.cgi?id=117689). The problem is that ContextMenuclient API changed in r182303, but we didn't notice it either, and the default handler for getContextMenuFromProposedMenu was executed. An override keyword would have caught this.
Created attachment 255343 [details]
Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See http://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API
Committed r185825: <http://trac.webkit.org/changeset/185825>