The for-in slow mode implementation in Crankshaft unconditionally
deoptimizes when %ForInFilter returns undefined instead of just
skipping the item. Even worse, there's nothing we can learn from
that deopt, so we will eventually optimize again and hit exactly
the same problem again once we get back to optimized code.
R=mvstanton@chromium.org
BUG=v8:3650
LOG=n
Review URL: https://codereview.chromium.org/1647093002
Cr-Commit-Position: refs/heads/master@{#33609}
