I haven't ever pushed this to try without some other stuff for bug 1193394, but it is possible that I've forgotten some mutation observer related tweak, which is in some other patch I have locally. But let's see what tryserver says. remote: View your change here: remote: https://hg.mozilla.org/try/rev/bec271413206a67485ca4704573da02e0c922bec remote: remote: Follow the progress of your build on Treeherder: remote: https://treeherder.mozilla.org/#/jobs?repo=try&revision=bec271413206a67485ca4704573da02e0c922bec remote: recorded changegroup in replication log in 0.029s Not sure who should review this, perhaps both you baku and bevis :)

oh, crap, I pushed with wrong try syntax

remote: View your change here: remote: https://hg.mozilla.org/try/rev/467f9f511a430bcbf9a94513ea86c580a740ad5b remote: remote: Follow the progress of your build on Treeherder: remote: https://treeherder.mozilla.org/#/jobs?repo=try&revision=467f9f511a430bcbf9a94513ea86c580a740ad5b remote: recorded changegroup in replication log in 0.016s

ok, that looks reasonable green.

Comment on attachment 8916610 [details] [diff] [review] make_mt_use_ccjs_microtasks.diff Review of attachment 8916610 [details] [diff] [review]: ----------------------------------------------------------------- ::: dom/base/nsDOMMutationObserver.cpp @@ +596,5 @@ > mWaitingForRun = true; > RescheduleForRun(); > } > > +class MutationObserverMicroTask : public MicroTaskRunnable final ? ::: xpcom/base/CycleCollectedJSContext.cpp @@ +438,5 @@ > > mPromiseMicroTaskQueue.push(runnable.forget()); > } > > +class AsyncMutationHandler : public mozilla::Runnable final

Comment on attachment 8916610 [details] [diff] [review] make_mt_use_ccjs_microtasks.diff Review of attachment 8916610 [details] [diff] [review]: ----------------------------------------------------------------- ::: xpcom/base/CycleCollectedJSContext.h @@ +237,5 @@ > { > mMicroTaskLevel = aLevel; > } > > void PerformMainThreadMicroTaskCheckpoint(); This could be removed now after all callsites are replaced with PerformMicroTaskCheckPoint().

Pushed by opettay@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/374ab23d114e Make CycleCollectedJSContext to handle microtasks and make MutationObserver to use them, r=baku,bevis