WebAutomationSession expects its client to be nullptr in the destructor.
Created attachment 318114 [details] Patch
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 r220786: <http://trac.webkit.org/changeset/220786>