Bug 1694017 - Accelerate 2x downscaling in SWGL. r=jrmuizel
Bug 1694017 - Accelerate 2x downscaling in SWGL. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D106302

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/ae5b26d89bf1c3cf135e1cd5f8fc8d064dd800f3

servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender