Revert "Fix build with WebKit master"

This reverts commit 23c3de000eddd33b8dfe2988dda10d01099505a7.

I don't think this is right, webkit_dom_element_get_class_list() is
defined in WebKitDOMElementUnstable.h now in WebKit master
Make it build with current WebKit master

WebKitWebViewGroup has been removed .