In case of an allocation failure in for-in over holey elements, use precise
number of elements to allocate a smaller buffer for the collected indices.

Drive-by-fix: make is_the_hole accept the isolate for faster checks.

BUG=chromium:609761

Review-Url: https://codereview.chromium.org/2041963003
Cr-Commit-Position: refs/heads/master@{#41010}