Bug 1306733: Don't crash on release builds if mTimer isn't set here. r=froydnj

MozReview-Commit-ID: eupSpSpJU3

--HG--
extra : rebase_source : d943f86b4bc015011f04f26fc8c2190f2472d111

xpcom/threads/TimerThread.cpp

@@ -270,7 +270,10 @@ nsTimerEvent::DeleteAllocatorIfNeeded()
 NS_IMETHODIMP
 nsTimerEvent::Run()
 {
-  MOZ_ASSERT(mTimer);
+  if (!mTimer) {
+    MOZ_ASSERT(false);
+    return NS_OK;
+  }
 
   if (mGeneration != mTimer->GetGeneration()) {
     return NS_OK;