The consume code cache code path was only taken in the case where the
isolate cache lookup failed, making the "hit isolate cache when consume
code cache" histogram sample never work.

Bug: chromium:769203
Change-Id: I15398f9ce4fc53602b323b8efb8ac9787440dd85
Reviewed-on: https://chromium-review.googlesource.com/765455Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49321}