Revert of Optimize trivial regexp disjunctions (patchset #10 id:180001 of https://codereview.chromium.org/1176453002/)

Reason for revert:
ASAN failure

Original issue's description:
> Optimize trivial regexp disjunctions
>
> R=yangguo@chromium.org
> BUG=chromium:482998
> LOG=n
>
> Committed: https://crrev.com/5f1f7c15b3207f6c51d187692690aeb09d3e36b5
> Cr-Commit-Position: refs/heads/master@{#28871}

TBR=yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:482998

Review URL: https://codereview.chromium.org/1174603002

Cr-Commit-Position: refs/heads/master@{#28878}