Revert of [debugger] temporarily re-implement --expose-debug-as. (patchset #1 id:1 of https://codereview.chromium.org/2636423002/ )

Reason for revert:
Flag is being removed for 5.8.

Original issue's description:
> [debugger] temporarily re-implement --expose-debug-as.
>
> This is done out of courtesy for Node.js and will be
> removed as soon as we branch for version 5.8.
>
> R=jgruber@chromium.org
>
> Review-Url: https://codereview.chromium.org/2636423002
> Cr-Commit-Position: refs/heads/master@{#42437}
> Committed: https://chromium.googlesource.com/v8/v8/+/cbb7145221dad688ebe86f90bfa4fdd63ea1263e

TBR=jgruber@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.

Review-Url: https://codereview.chromium.org/2641283002
Cr-Commit-Position: refs/heads/master@{#42546}