Reason for revert:
[Sheriff] Seems to break layout tests:
http://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/2073

https://storage.googleapis.com/chromium-layout-test-archives/V8-Blink_Linux_64/2073/layout-test-results/results.html

Please request rebaseline upstream first.

Original issue's description:
> Clean up rewriter.
>
> The main changes are:
> - Fix treatment of loops, which was incorrect and sometimes resulted in
>   the wrong completion value.
> - Get rid of unnecessary variables.
>
> This is in preparation of implementing ES6 completion semantics.
>
> R=rossberg
> BUG=
>
> Committed: https://crrev.com/b466dc14791844b7ae6d1e9ebd00a778965c206d
> Cr-Commit-Position: refs/heads/master@{#30981}

TBR=rossberg@chromium.org,neis@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1379513002

Cr-Commit-Position: refs/heads/master@{#30992}