Unreviewed GTK build fix after r159896.

* UIProcess/API/gtk/WebKitWebContext.cpp:
(webkitWebContextCreatePageForWebView):
* UIProcess/API/gtk/WebKitWebView.cpp:
(webkitWebViewConstructed):
* UIProcess/API/gtk/WebKitWebViewBase.cpp:
(webkitWebViewBaseUpdatePreferences):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@159899 268f45cc-cd09-0410-ab3c-d52691b4dbfc