We should just steal the code to do that from gir-repository in git.gnome.org, and add it to our package. When that's done they can remove it from their side, which is just a temporary repository until all the packages in the platform do the right thing.
Created attachment 39988 [details] introspection.diff Add introspection support to WebKitGTK+.
Comment on attachment 39988 [details] introspection.diff r=me
Thanks, landed in r48670.