Revert of Re-land new insertion write barrier. (patchset #1 id:1 of https://codereview.chromium.org/1211513002/)

Reason for revert:
Still crashing in the wild.

Original issue's description:
> Re-land new insertion write barrier.
>
> BUG=
>
> Committed: https://crrev.com/6e6af7e7c70050cdd5ce56cdbaee3b6e8a7caa89
> Cr-Commit-Position: refs/heads/master@{#29258}

TBR=ulan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1217443002

Cr-Commit-Position: refs/heads/master@{#29320}