Bug 1261143 - Hack recursion depth in metastable state for Mac OS. r=khuey

xpcom/base/CycleCollectedJSRuntime.cpp

@@ -1421,6 +1421,13 @@ CycleCollectedJSRuntime::RunInMetastableState(already_AddRefed<nsIRunnable>&& aR
   // There must be an event running to get here.
 #ifndef MOZ_WIDGET_COCOA
   MOZ_ASSERT(data.mRecursionDepth > mBaseRecursionDepth);
+#else
+  // XXX bug 1261143
+  // Recursion depth should be greater than mBaseRecursionDepth,
+  // or the runnable will stay in the queue forever.
+  if (data.mRecursionDepth <= mBaseRecursionDepth) {
+    data.mRecursionDepth = mBaseRecursionDepth + 1;
+  }
 #endif
 
   mMetastableStateEvents.AppendElement(Move(data));