1) Function recording conditions need to be consistent (this same condition is used above)

2) byte is not wide enough for storing the backing store size.

Bugs uncovered by the existing tests with the flag on.

BUG=v8:5516

Change-Id: Iec6aff0cf1858afe1083526e4ada9a8eca08f062
Reviewed-on: https://chromium-review.googlesource.com/481320
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44724}