This saves ~1:30 of overhead when the isolate cache is warm.
Bug: skia:5813
Change-Id: I5053d66e865ca6500b82567f83be8042568e22cf
Reviewed-on: https://skia-review.googlesource.com/11063
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
