In https://chromium-review.googlesource.com/c/509693/ the From
keyword was removed. This update the script to match that (we
also were no longer using it).

BUG=libyuv:704
NOTRY=True

Change-Id: Iccbbfb426a3acd986fbc036672fb51abc2c5d346
Reviewed-on: https://chromium-review.googlesource.com/513908Reviewed-by: Frank Barchard <fbarchard@google.com>
Commit-Queue: Henrik Kjellander <kjellander@chromium.org>