Revert of [heap] Separate out optimized code map processing. (patchset #2 id:20001 of https://codereview.chromium.org/1421903012/ )

Reason for revert:
Causes GC-Stress failures.

Original issue's description:
> [heap] Separate out optimized code map processing.
>
> This separates the post-processing step for optimized code maps out of
> the CodeFlusher. It uses the complete SharedFunctionInfo::Iterator to
> visit all candidates instead of gathering candidates during marking.
>
> Gathering candidates during marking no longer makes sense, now that the
> majority of SharedFunctionInfo objects will hold such an optimized code
> map. Also it reduces complexity of the implementation. Also conflating
> this mechanism with "code flushing" was confusing.
>
> This reverts commit b6644e84.
>
> R=ulan@chromium.org
>
> Committed: https://crrev.com/bb7a5eb2d89bae25f2b5ecb9515669f0ac73c111
> Cr-Commit-Position: refs/heads/master@{#31836}

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

Review URL: https://codereview.chromium.org/1412063012

Cr-Commit-Position: refs/heads/master@{#31837}