Bug 928403 - optimize nsFrameConstructorState::ProcessFrameInsertions, r=roc

--HG--
rename : testing/mochitest/b2g-debug.json => testing/mochitest/b2g.json
extra : rebase_source : c45d39f4b50f248b28a6ebfb50128084bb59ebe4
Bug 914847. Use a mini-flush instead of a full style flush. r=dbaron
Bug 914847. Mini-flush for animations. r=dbaron