This will allow it to eliminate more redundant CheckStructures. This is only going to be a tiny win, since the bytecode parser usually eliminates these (it only misses those cases that are later revealed by CFG simplification). But it's an easy change, so it's worth it.
Created attachment 143393 [details] the patch
Landed in http://trac.webkit.org/changeset/118141
Merged in http://trac.webkit.org/changeset/118582