Revert of [debugger] correctly find source position of implicit return statement. (patchset #1 id:1 of https://codereview.chromium.org/1521953003/ )

Reason for revert:
Layout test failures: https://chromegw.corp.google.com/i/client.v8.fyi/builders/V8-Blink%20Mac/builds/2732/steps/webkit_tests%20%28with%20patch%29/logs/stdio

Original issue's description:
> [debugger] correctly find source position of implicit return statement.
>
> The parser reads one character beyond EOF to have an additional source
> position that the rewriter can use to insert the implicit return
> statement at the end of a script. If we break at that return statement,
> we need to be able to translate the source position to line and
> column number.
>
> R=jkummerow@chromium.org
>
> Committed: https://crrev.com/0b1076a68e1eadba260cec8afc5acec618561c28
> Cr-Commit-Position: refs/heads/master@{#32825}

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

Review URL: https://codereview.chromium.org/1526583002

Cr-Commit-Position: refs/heads/master@{#32829}