Revert of [heap] Enable black allocation. (patchset #1 id:1 of https://codereview.chromium.org/1809983002/ )

Reason for revert:
Continues to cause flaky GPU test failures on Chromium waterfall.
See details at http://crbug.com/595092#c22

Original issue's description:
> [heap] Enable black allocation.
>
> BUG=
>
> Committed: https://crrev.com/447b1156d3bb4aa693175b74780104329ccd41ea
> Cr-Commit-Position: refs/heads/master@{#34847}

TBR=mlippautz@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:595092

Review URL: https://codereview.chromium.org/1807393002

Cr-Commit-Position: refs/heads/master@{#34877}