Revert of Auto-generate v8 version based on tags. (patchset #5 id:80001 of https://codereview.chromium.org/797503007/)

Reason for revert:
Blocks roll on android_aosp:
https://codereview.chromium.org/851953005/

Original issue's description:
> Auto-generate v8 version based on tags.
>
> BUG=chromium:446166
> LOG=y
>
> Committed: https://crrev.com/b301b85be895c6fcd1edfe2fd1e60b5abd0ac64d
> Cr-Commit-Position: refs/heads/master@{#26062}

TBR=jochen@chromium.org,jkummerow@chromium.org,tandrii@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=chromium:446166

Review URL: https://codereview.chromium.org/850263002

Cr-Commit-Position: refs/heads/master@{#26067}