This may not be needed for performance and it's not needed for correctness, but it seems like a hole in the design. Experience has shown that anytime we make a compilation plan not cancellable, there ends up being some benchmark where this introduces object drag.
I'm actually just going to do this as https://bugs.webkit.org/show_bug.cgi?id=132166. *** This bug has been marked as a duplicate of bug 132166 ***