Bug 1768652: Make sure to always cancel the sceneswap timer when not recording. r=jrmuizel
Bug 1768652: Make sure to always cancel the sceneswap timer when not recording. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D145968

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/9a7f8fc8770b559d1076e3e816331c8f6588adff

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