The change to use emitJumpIfNotType results in problems, because this function is often called (in 32-bit mode) with the tag register as the scratch register. If the jump is taken, the slow path code then expects the tag register to be intact, and passes the no-longer-valid tag to a stub function. This results in failures when attempting to make InternalFunction calls.
Created attachment 108305 [details] the patch
Comment on attachment 108305 [details] the patch r+ to go ahead. I tested it on a 32-bit Qt environment and it works for me.
Comment on attachment 108305 [details] the patch Clearing flags on attachment: 108305 Committed r95707: <http://trac.webkit.org/changeset/95707>
All reviewed patches have been landed. Closing bug.