Revert "In the CPU backend, stop treating alpha images as coverage"

Restore the old behavior behind a flag, so it can be maintained in the
Android framework.

This reverts commit f1660bf1baecb787f5d541c1973f2c7f2ded13dd.

Bug: b/231400686
Test: GM in Skia
Change-Id: I01fadaed52eecc42416deb2307d03499bca85a4c
Reviewed-by: Michael Ludwig <>
Commit-Queue: Brian Osman <>
Reviewed-by: Leon Scroggins <>
(cherry picked from commit fa93c4addd3cfba3054d34f30d5d4b61af2821be)
Merged-In: I01fadaed52eecc42416deb2307d03499bca85a4c
5 files changed