We regressed sunspider +- 2% because SS-fannkuch has regressed with 60% on October 17th, 2013. Regression range is: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=dca0f18f3e86&tochange=5a58e6669962 Manually running a bisect gives: Bug 925962 - Track expected contents of stack type sets in compiler constraints

In fannkuch the first IonScript that is built gets invalidated as one of the inner |if| statements hasn't executed yet and populates some new stack type sets when it does. This happened both before and after the 785905 stuff, but now we detect the invalidation when finishing the compilation and immediately rebuild the script. That isn't great, as the script should be reprimed in baseline by resetting its use count to gather more type information. This patch makes that fix, and improves fannkuch perf a good deal. It is still about 10% slower than before bug 921902, though that will improve once bug 785905 is (finally) done.