Revert of [serializer/debugger] hide scripts in the snapshot from the debugger. (patchset #5 id:80001 of https://codereview.chromium.org/2826073004/ )

Reason for revert:
failure in the custom snapshot build: http://builders/V8%20Linux64%20-%20custom%20snapshot%20-%20debug/builds/14178

Original issue's description:
> [serializer/debugger] hide scripts in the snapshot from the debugger.
>
> R=jgruber@chromium.org
> BUG=v8:6274
>
> Review-Url: https://codereview.chromium.org/2826073004
> Cr-Commit-Position: refs/heads/master@{#44745}
> Committed: https://chromium.googlesource.com/v8/v8/+/215e668256a205aba7bacf2da8b68ddfc573d3dd

TBR=jgruber@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:6274

Review-Url: https://codereview.chromium.org/2831893002
Cr-Commit-Position: refs/heads/master@{#44747}