Bug 1699013 - Avoid assertion in the image tiling code. r=jnicol
Bug 1699013 - Avoid assertion in the image tiling code. r=jnicol

We can gracefully handle null stride when there's no visible rect since it should always result in an empty iterator.

Differential Revision: https://phabricator.services.mozilla.com/D110089

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/bb62a924a4ed0ac6f135e375ff1a6cc3238b084e

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