Bug
1768058: Add wrench tests for opacity on stretched images. r=gw
Bug
1752919 fixed the opacity issues for tiled images. This is an attempt to
replicate the testcases from that bug. The wrench frame capture of the problem case
shows Image display items with alpha color applied. This patch updates the yaml
frame reader to process color on Images, and the "image-alpha" wrench tests recreate
that scene. For completeness' sake, the tests also check opacity derived from the
stacking context (which already worked).
Differential Revision: https://phabricator.services.mozilla.com/
D147442