Bug 1591758 - Fix dirty rects for OS compositors without partial updates. r=nical
Bug 1591758 - Fix dirty rects for OS compositors without partial updates. r=nical

Differential Revision: https://phabricator.services.mozilla.com/D51773

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/95dfa337c1dbb77e210abc30790ccb49ff7e163b

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