Fix WebKit Bugzilla links

The bugs.webengine.org domain does not exist.

Change-Id: I70ffb181e20e7c96ca3e6e32ee55b49b21f5bd9f
Reviewed-by: Adam Kallai <kadam@inf.u-szeged.hu>
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>