Revert of [cq] Temporarily make failing chromium trybot experimental (patchset #1 id:1 of https://codereview.chromium.org/2352573002/ )

Reason for revert:
Real fix landed by now.

Original issue's description:
> [cq] Temporarily make failing chromium trybot experimental
>
> BUG=chromium:648153
> NOTRY=true
> NOPRESUBMIT=true
> TBR=emso@chromium.org
>
> Committed: https://crrev.com/bb6fa481b6e8e643cb86d66cfa5b8bb35d1dd320
> Cr-Commit-Position: refs/heads/master@{#39494}

TBR=emso@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:648153

Review-Url: https://codereview.chromium.org/2353713002
Cr-Commit-Position: refs/heads/master@{#39516}