Revert of New insertion write barrier. (patchset #3 id:200001 of https://codereview.chromium.org/1073953006/)

Reason for revert:
Various performance regressions.

Original issue's description:
> New insertion write barrier.
>
> BUG=
>
> Committed: https://crrev.com/6e9e2c08292b553602c74b16b8ccff4e4ccac003
> Cr-Commit-Position: refs/heads/master@{#28199}

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

Review URL: https://codereview.chromium.org/1131583002

Cr-Commit-Position: refs/heads/master@{#28265}