--- a/dom/broadcastchannel/BroadcastChannel.cpp
+++ b/dom/broadcastchannel/BroadcastChannel.cpp
@@ -120,58 +120,16 @@ public:
 
 private:
   RefPtr<ThreadSafeWorkerRef> mWorkerRef;
   nsACString& mOrigin;
   PrincipalInfo& mPrincipalInfo;
   ErrorResult& mRv;
 };
 
-class BCPostMessageRunnable final : public nsIRunnable,
-                                    public nsICancelableRunnable
-{
-public:
-  NS_DECL_ISUPPORTS
-
-  BCPostMessageRunnable(BroadcastChannelChild* aActor,
-                        BroadcastChannelMessage* aData)
-    : mActor(aActor)
-    , mData(aData)
-  {
-    MOZ_ASSERT(mActor);
-  }
-
-  NS_IMETHOD Run() override
-  {
-    MOZ_ASSERT(mActor);
-    if (mActor->IsActorDestroyed()) {
-      return NS_OK;
-    }
-
-    ClonedMessageData message;
-    mData->BuildClonedMessageDataForBackgroundChild(mActor->Manager(), message);
-    mActor->SendPostMessage(message);
-    return NS_OK;
-  }
-
-  nsresult Cancel() override
-  {
-    mActor = nullptr;
-    return NS_OK;
-  }
-
-private:
-  ~BCPostMessageRunnable() {}
-
-  RefPtr<BroadcastChannelChild> mActor;
-  RefPtr<BroadcastChannelMessage> mData;
-};
-
-NS_IMPL_ISUPPORTS(BCPostMessageRunnable, nsICancelableRunnable, nsIRunnable)
-
 class CloseRunnable final : public nsIRunnable,
                             public nsICancelableRunnable
 {
 public:
   NS_DECL_ISUPPORTS
 
   explicit CloseRunnable(BroadcastChannel* aBC)
     : mBC(aBC)
@@ -393,45 +351,28 @@ void
 BroadcastChannel::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
                               ErrorResult& aRv)
 {
   if (mState != StateActive) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
 
-  PostMessageInternal(aCx, aMessage, aRv);
-}
-
-void
-BroadcastChannel::PostMessageInternal(JSContext* aCx,
-                                      JS::Handle<JS::Value> aMessage,
-                                      ErrorResult& aRv)
-{
   RefPtr<BroadcastChannelMessage> data = new BroadcastChannelMessage();
 
   data->Write(aCx, aMessage, aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     return;
   }
 
-  PostMessageData(data);
-}
-
-void
-BroadcastChannel::PostMessageData(BroadcastChannelMessage* aData)
-{
   RemoveDocFromBFCache();
 
-  RefPtr<BCPostMessageRunnable> runnable =
-    new BCPostMessageRunnable(mActor, aData);
-
-  if (NS_FAILED(NS_DispatchToCurrentThread(runnable))) {
-    NS_WARNING("Failed to dispatch to the current thread!");
-  }
+  ClonedMessageData message;
+  data->BuildClonedMessageDataForBackgroundChild(mActor->Manager(), message);
+  mActor->SendPostMessage(message);
 }
 
 void
 BroadcastChannel::Close()
 {
   if (mState != StateActive) {
     return;
   }

--- a/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js
+++ b/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js
@@ -1,8 +1,7 @@
-(new BroadcastChannel('foobar')).postMessage('READY');
-
 (new BroadcastChannel('foobar')).addEventListener('message', function(event) {
   if (event.data != 'READY') {
     event.target.postMessage(event.data);
   }
 });
 
+(new BroadcastChannel('foobar')).postMessage('READY');

--- a/dom/broadcastchannel/tests/test_event_listener_leaks.html
+++ b/dom/broadcastchannel/tests/test_event_listener_leaks.html
@@ -18,20 +18,20 @@
 // exercise the leak condition.
 let count = 0;
 async function useBroadcastChannel(contentWindow) {
   contentWindow.messageCount = 0;
 
   count += 1;
   const name = `test_event_listener_leaks-${count}`;
 
+  let bc = new contentWindow.BroadcastChannel(name);
   let outer = new BroadcastChannel(name);
   outer.postMessage('foo');
 
-  let bc = new contentWindow.BroadcastChannel(name);
   await new Promise(resolve => {
     bc.onmessage = e => {
       contentWindow.messageCount += 1;
       resolve();
     };
   });
 
   is(contentWindow.messageCount, 1, "message should be received");