Revert of Allow Math.random to be called when creating a custom startup snapshot. (patchset #2 id:20001 of https://codereview.chromium.org/1780173002/ )

Reason for revert:
Regresses performance on base64 benchmark.

Original issue's description:
> Allow Math.random to be called when creating a custom startup snapshot.
>
> R=jkummerow@chromium.org
> BUG=v8:4810
> LOG=N
>
> Committed: https://crrev.com/6a7ec6a3bf779cdd41c66a768fd7a37195ed7b7f
> Cr-Commit-Position: refs/heads/master@{#34705}

TBR=jkummerow@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=v8:4810, chromium:594484
LOG=N

Review URL: https://codereview.chromium.org/1798863003

Cr-Commit-Position: refs/heads/master@{#34739}