Revert of Shrink initial old generation size based on new space survival rate. (patchset #7 id:140001 of https://codereview.chromium.org/785593002/)

Reason for revert:
Performance regressions.

Original issue's description:
> Shrink initial old generation size based on new space  survival rate.
>
> BUG=
>
> Committed: https://crrev.com/37f9bb72b9c7ea4eccef6cb6533b3c42792fb5e6
> Cr-Commit-Position: refs/heads/master@{#25850}

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

Review URL: https://codereview.chromium.org/813733002

Cr-Commit-Position: refs/heads/master@{#25862}
[turbofan] Improve reduction of Word32And and Int32Add.

TEST=unittests
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/816433002

Cr-Commit-Position: refs/heads/master@{#25863}
[turbofan] use START and END gap positions for constraints

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/798363007

Cr-Commit-Position: refs/heads/master@{#25864}