Bug 1580922 - changing the blob visible area can require rasterization requests. r=jrmuizel
Bug 1580922 - changing the blob visible area can require rasterization requests. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D47084

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/31d0469993bdecfcad267a2e0eaedc18e1199848

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