Bug 1625693 - Fix mouse movement position tracking in examples. r=kats
Bug 1625693 - Fix mouse movement position tracking in examples. r=kats

[import_pr] From https://github.com/servo/webrender/pull/3961

Differential Revision: https://phabricator.services.mozilla.com/D76716

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/7ced9547a2b33307774e5292aa9f787109633267

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