Bug 1642629 - Reserve GpuBlockData vector before pushing in a loop. r=kvark
Bug 1642629 - Reserve GpuBlockData vector before pushing in a loop. r=kvark

Differential Revision: https://phabricator.services.mozilla.com/D80203

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/a16036b4b36cfa4dc083fa5a6fbc3db0adbc978f

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