Web Inspector: remove dead code related to changes panel (no updates since August 2009).
Created attachment 81070 [details] Patch.
Committed r77510: <http://trac.webkit.org/changeset/77510>
http://trac.webkit.org/changeset/77510 might have broken GTK Linux 64-bit Debug The following tests are not passing: editing/selection/end-of-document.html