--- a/xpcom/ds/Observer.h
+++ b/xpcom/ds/Observer.h
@@ -52,50 +52,32 @@ public:
   }
 
   /**
    * Remove the observer from the observer list.
    * @return Whether the observer has been found in the list.
    */
   bool RemoveObserver(Observer<T>* aObserver)
   {
-    if (mObservers.RemoveElement(aObserver)) {
-      // Annoyingly, someone could RemoveObserver() an item on the list
-      // while we're in a Broadcast()'s Notify() call.
-      auto i = mBroadcastCopy.IndexOf(aObserver);
-      MOZ_ASSERT(i != mBroadcastCopy.NoIndex);
-      mBroadcastCopy[i] = nullptr;
-      return true;
-    }
-    return false;
+    return mObservers.RemoveElement(aObserver);
   }
 
   uint32_t Length()
   {
     return mObservers.Length();
   }
 
-  /**
-   * Call Notify() on each item in the list.
-   * Handles the case of Notify() calling RemoveObserver()
-   */
   void Broadcast(const T& aParam)
   {
-    MOZ_ASSERT(mBroadcastCopy.IsEmpty());
-    mBroadcastCopy = mObservers;
-    uint32_t size = mBroadcastCopy.Length();
+    nsTArray<Observer<T>*> observersCopy(mObservers);
+    uint32_t size = observersCopy.Length();
     for (uint32_t i = 0; i < size; ++i) {
-      // nulled if Removed during Broadcast
-      if (mBroadcastCopy[i]) {
-        mBroadcastCopy[i]->Notify(aParam);
-      }
+      observersCopy[i]->Notify(aParam);
     }
-    mBroadcastCopy.Clear();
   }
 
 protected:
   nsTArray<Observer<T>*> mObservers;
-  nsTArray<Observer<T>*> mBroadcastCopy;
 };
 
 } // namespace mozilla
 
 #endif // mozilla_Observer_h