This mitigates the problem of blocking on the main thread when the
platform is unable to execute background tasks in a timely manner.

Bug: v8:6671
Change-Id: I741d4b7594e8d62721dad32cbfb19551ffacd0c3
Reviewed-on: https://chromium-review.googlesource.com/599528
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47126}