Revert of Debugger: deduplicate shared function info when setting script break points. (patchset #4 id:60001 of https://codereview.chromium.org/998253005/)

Reason for revert:
Code caching failures.

Original issue's description:
> Debugger: deduplicate shared function info when setting script break points.
>
> Also fix Debug.showBreakPoints for multiple break points at the same location.
>
> BUG=v8:3960
> LOG=N
>
> Committed: https://crrev.com/73b17a71a22564c0b66d9aa7c00948c748f5b290
> Cr-Commit-Position: refs/heads/master@{#27444}

TBR=mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3960

Review URL: https://codereview.chromium.org/999273003

Cr-Commit-Position: refs/heads/master@{#27448}