Bug 1391850 - Allow IdleDispatch from any thread (r=smaug)

MozReview-Commit-ID: FWb48VV0do8

xpcom/threads/nsThread.cpp

@@ -821,12 +821,6 @@ nsThread::HasPendingEvents(bool* aResult)
 NS_IMETHODIMP
 nsThread::IdleDispatch(already_AddRefed<nsIRunnable> aEvent)
 {
-  // Currently the only supported idle dispatch is from the same
-  // thread. To support idle dispatch from another thread we need to
-  // support waking threads that are waiting for an event queue that
-  // isn't mIdleEvents.
-  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
-
   nsCOMPtr<nsIRunnable> event = aEvent;
 
   if (NS_WARN_IF(!event)) {