This is due to the recent moving of property toggling checkboxes to the left. Patch to follow.
Created attachment 127812 [details] Patch
Created attachment 127813 [details] [PATCH] Fixed margin (should be 6px, not 5px)
Created attachment 127814 [details] [PATCH] Correct version of the patch
Committed r108236: <http://trac.webkit.org/changeset/108236>