Bug 1641142: Fix rounding error when clamping blur radius r=gfx-reviewers,nical
Bug 1641142: Fix rounding error when clamping blur radius r=gfx-reviewers,nical

Differential Revision: https://phabricator.services.mozilla.com/D77187

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/0f1e35bee5748fc5d8c5f2043d32c16ed261c99b

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