angle: Stop setting secondary_source.
angle: Stop setting secondary_source.

It's no longer needed.

Bug: chromium:947060
Change-Id: I873f17a4876b9d0fac313740853054b6867afeb9
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1610077
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Commit-Queue: Nico Weber <c0f02d98506190746d1cdcb01be0f37b51e27077@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle