This reverts commit 4dc19c38.

Causes a git error during 'gn gen':
  fatal: this operation must be run in a work tree

BUG=chromium:1055991,angleproject:2344

Change-Id: I74dd36d557dcaf1bd1b13264d806a1c6b09e1a56
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2073200Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>