Revert of [gn] Add unittests (patchset #6 id:100001 of https://codereview.chromium.org/2011853002/ )

Reason for revert:
http://crbug.com/615890

Original issue's description:
> [gn] Add unittests
>
> BUG=chromium:474921
> NOTRY=true
>
> Committed: https://crrev.com/67e549ec5b34ad02506abb2720c6a0851ae31f5e
> Cr-Commit-Position: refs/heads/master@{#36510}
>
> Committed: https://crrev.com/143b3d167d7014525d049d3ab53c73cf2592243c
> Cr-Commit-Position: refs/heads/master@{#36582}

TBR=vogelheim@chromium.org,bmeurer@chromium.org,jochen@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:474921

Review-Url: https://codereview.chromium.org/2022893002
Cr-Commit-Position: refs/heads/master@{#36605}