--- a/dom/base/WebSocket.cpp
+++ b/dom/base/WebSocket.cpp
@@ -75,20 +75,17 @@ class WebSocketImpl final : public nsIIn
 {
 public:
   NS_DECL_NSIINTERFACEREQUESTOR
   NS_DECL_NSIWEBSOCKETLISTENER
   NS_DECL_NSIOBSERVER
   NS_DECL_NSIREQUEST
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIEVENTTARGET
-  // missing from NS_DECL_NSIEVENTTARGET because MSVC
-  nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-    return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-  }
+  using nsIEventTarget::Dispatch;
 
   explicit WebSocketImpl(WebSocket* aWebSocket)
   : mWebSocket(aWebSocket)
   , mOnCloseScheduled(false)
   , mFailed(false)
   , mDisconnectingOrDisconnected(false)
   , mCloseEventWasClean(false)
   , mCloseEventCode(nsIWebSocketChannel::CLOSE_ABNORMAL)

--- a/netwerk/base/nsSocketTransportService2.h
+++ b/netwerk/base/nsSocketTransportService2.h
@@ -76,20 +76,17 @@ public:
     NS_DECL_THREADSAFE_ISUPPORTS
     NS_DECL_NSPISOCKETTRANSPORTSERVICE
     NS_DECL_NSISOCKETTRANSPORTSERVICE
     NS_DECL_NSIROUTEDSOCKETTRANSPORTSERVICE
     NS_DECL_NSIEVENTTARGET
     NS_DECL_NSITHREADOBSERVER
     NS_DECL_NSIRUNNABLE
     NS_DECL_NSIOBSERVER 
-    // missing from NS_DECL_NSIEVENTTARGET because MSVC
-    nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-      return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-    }
+    using nsIEventTarget::Dispatch;
 
     nsSocketTransportService();
 
     // Max Socket count may need to get initialized/used by nsHttpHandler
     // before this class is initialized.
     static uint32_t gMaxCount;
     static PRCallOnceType gMaxCountInitOnce;
     static PRStatus DiscoverMaxCount();

--- a/netwerk/base/nsStreamTransportService.h
+++ b/netwerk/base/nsStreamTransportService.h
@@ -16,20 +16,17 @@ class nsStreamTransportService final : p
                                      , public nsIEventTarget
                                      , public nsIObserver
 {
 public:
     NS_DECL_THREADSAFE_ISUPPORTS
     NS_DECL_NSISTREAMTRANSPORTSERVICE
     NS_DECL_NSIEVENTTARGET
     NS_DECL_NSIOBSERVER
-    // missing from NS_DECL_NSIEVENTTARGET because MSVC
-    nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-      return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-    }
+    using nsIEventTarget::Dispatch;
 
     nsresult Init();
 
     nsStreamTransportService() : mShutdownLock("nsStreamTransportService.mShutdownLock"),
                                  mIsShutdown(false) {}
 
 private:
     ~nsStreamTransportService();

--- a/xpcom/threads/LazyIdleThread.h
+++ b/xpcom/threads/LazyIdleThread.h
@@ -40,20 +40,17 @@ class LazyIdleThread final
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIEVENTTARGET
   NS_DECL_NSITHREAD
   NS_DECL_NSITIMERCALLBACK
   NS_DECL_NSITHREADOBSERVER
   NS_DECL_NSIOBSERVER
-  // missing from NS_DECL_NSIEVENTTARGET because MSVC
-  nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-    return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-  }
+  using nsIEventTarget::Dispatch;
 
   enum ShutdownMethod
   {
     AutomaticShutdown = 0,
     ManualShutdown
   };
 
   /**

--- a/xpcom/threads/SharedThreadPool.h
+++ b/xpcom/threads/SharedThreadPool.h
@@ -50,27 +50,25 @@ public:
   // in a tight loop.
   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;
   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;
   NS_IMETHOD_(MozExternalRefCountType) Release(void) override;
 
   // Forward behaviour to wrapped thread pool implementation.
   NS_FORWARD_SAFE_NSITHREADPOOL(mPool);
 
-  // See bug 1155059 - MSVC forces us to not declare Dispatch normally in idl
-  //  NS_FORWARD_SAFE_NSIEVENTTARGET(mEventTarget);
-  nsresult Dispatch(nsIRunnable *event, uint32_t flags) { return !mEventTarget ? NS_ERROR_NULL_POINTER : mEventTarget->Dispatch(event, flags); }
- 
   NS_IMETHOD DispatchFromScript(nsIRunnable *event, uint32_t flags) override {
       return Dispatch(event, flags);
   }
 
   NS_IMETHOD Dispatch(already_AddRefed<nsIRunnable>&& event, uint32_t flags) override
     { return !mEventTarget ? NS_ERROR_NULL_POINTER : mEventTarget->Dispatch(Move(event), flags); }
 
+  using nsIEventTarget::Dispatch;
+
   NS_IMETHOD IsOnCurrentThread(bool *_retval) override { return !mEventTarget ? NS_ERROR_NULL_POINTER : mEventTarget->IsOnCurrentThread(_retval); }
 
   // Creates necessary statics. Called once at startup.
   static void InitStatics();
 
   // Spins the event loop until all thread pools are shutdown.
   // *Must* be called on the main thread.
   static void SpinUntilEmpty();

--- a/xpcom/threads/nsIEventTarget.idl
+++ b/xpcom/threads/nsIEventTarget.idl
@@ -12,21 +12,16 @@
 %}
 
 native alreadyAddRefed_nsIRunnable(already_AddRefed<nsIRunnable>&&);
 
 [scriptable, uuid(f9d60700-e6dc-4a72-9537-689058655472)]
 interface nsIEventTarget : nsISupports
 {
   /* until we can get rid of all uses, keep the non-alreadyAddRefed<> version */
-  /**
-   * This must be non-virtual due to issues with MSVC 2013's ordering of
-   * vtbls for overloads.  With other platforms we can leave this virtual
-   * and avoid adding lots of Dispatch() methods to classes inheriting this.
-   */
 %{C++
     nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
       return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
     }
 %}
 
   /**
    * This flag specifies the default mode of event dispatch, whereby the event

--- a/xpcom/threads/nsThread.h
+++ b/xpcom/threads/nsThread.h
@@ -28,20 +28,17 @@ class nsThread
   , public nsISupportsPriority
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIEVENTTARGET
   NS_DECL_NSITHREAD
   NS_DECL_NSITHREADINTERNAL
   NS_DECL_NSISUPPORTSPRIORITY
-  // missing from NS_DECL_NSIEVENTTARGET because MSVC
-  nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-    return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-  }
+  using nsIEventTarget::Dispatch;
 
   enum MainThreadFlag
   {
     MAIN_THREAD,
     NOT_MAIN_THREAD
   };
 
   nsThread(MainThreadFlag aMainThread, uint32_t aStackSize);

--- a/xpcom/threads/nsThreadPool.h
+++ b/xpcom/threads/nsThreadPool.h
@@ -23,20 +23,17 @@ class nsThreadPool final
   : public nsIThreadPool
   , public nsIRunnable
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIEVENTTARGET
   NS_DECL_NSITHREADPOOL
   NS_DECL_NSIRUNNABLE
-  // missing from NS_DECL_NSIEVENTTARGET because MSVC
-  nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
-    return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-  }
+  using nsIEventTarget::Dispatch;
 
   nsThreadPool();
 
 private:
   ~nsThreadPool();
 
   void ShutdownThread(nsIThread* aThread);
   nsresult PutEvent(nsIRunnable* aEvent);