This reverts commit 1d6478a5.

Reason for revert: 
Skia doesn't pass target refs to patches yet.

Original change's description:
> gclient: Require a target ref when applying patches.
> 
> Bug: 956807
> Change-Id: Icfffe965f9f4651f22e8ba32c60133a5620bb350
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1616804
> Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

TBR=tandrii@chromium.org,ehmaldonado@chromium.org

Change-Id: I96c7d4ab7df151f50e82f783ef1a8769890aef9a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 956807
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1623593Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>