This fix is important because when we are here: https://dxr.mozilla.org/mozilla-central/source/dom/workers/WorkerPrivate.cpp#5838 with aStatus == Terminating, we create the CloseEventRunnable runnable: if (previousStatus == Running && aStatus != Killing) { MOZ_ASSERT(!mCloseHandlerStarted && !mCloseHandlerFinished); RefPtr<CloseEventRunnable> closeRunnable = new CloseEventRunnable(this); then few lines after we do: https://dxr.mozilla.org/mozilla-central/source/dom/workers/WorkerPrivate.cpp#5856 if (aStatus == Terminating) { // Only abort the script if we're not yet running the close handler. return mCloseHandlerStarted; } and re always returns false because the closeEventRunnable has not been executed yet. We have a similar pattern when aStatus == Canceling.

Pushed by amarchesini@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/ba6b75f29652 CloseHandlerStarted() is called wrongly in WorkerPrivate, r=khuey

Hi baku, have backed this out due to W-e10s failures, e.g. https://treeherder.mozilla.org/logviewer.html#?job_id=32331215&repo=mozilla-inbound#L4263

Backout by ihsiao@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/d3c449980296 Backed out changeset ba6b75f29652 for web platform e10s test failure

I'll merge this patch in some other bug when needed.

Bug 790919 removes CloseHandlerStarted completely