Previously we would directly take the result from a fulfilled native
promise bypassing the microtask queue. This is observably different
from the spec.

Note: Our variant of the bluebird benchmark is heavily favored towards
fulfilled native promises because we don't use setTimeout (unlike the
original benchmark). I suspect this pattern doesn't appear often in
the wild so it's fine to take this hit for now.

PSA for Perf sheriffs: this is going to tank some benchmarks.

Bug: chromium:800651, v8:5691, v8:6007
Change-Id: Ic273bf2195529424b0d87359d28d5267060d5252
Reviewed-on: https://chromium-review.googlesource.com/895416
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51010}