diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index b2dd845f69e1..931ca8fae063 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -326,7 +326,6 @@ nsHtml5StringParser* nsContentUtils::sHTMLFragmentParser = nullptr;
 nsIParser* nsContentUtils::sXMLFragmentParser = nullptr;
 nsIFragmentContentSink* nsContentUtils::sXMLFragmentSink = nullptr;
 bool nsContentUtils::sFragmentParsingActive = false;
-nsISerialEventTarget* nsContentUtils::sStableStateEventTarget = nullptr;
 
 #if !(defined(DEBUG) || defined(MOZ_ENABLE_JS_DUMP))
 bool nsContentUtils::sDOMWindowDumpEnabled;
@@ -520,52 +519,6 @@ class SameOriginCheckerImpl final : public nsIChannelEventSink,
   NS_DECL_NSIINTERFACEREQUESTOR
 };
 
-class StableStateEventTarget final : public nsISerialEventTarget
-{
-public:
-  NS_DECL_THREADSAFE_ISUPPORTS
-  NS_DECL_NSIEVENTTARGET_FULL
-private:
-  ~StableStateEventTarget() {}
-};
-
-NS_IMPL_ISUPPORTS(StableStateEventTarget, nsISerialEventTarget);
-
-bool
-StableStateEventTarget::IsOnCurrentThreadInfallible()
-{
-  return true;
-}
-
-NS_IMETHODIMP
-StableStateEventTarget::IsOnCurrentThread(bool* aResult)
-{
-  *aResult = true;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-StableStateEventTarget::Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
-{
-  if (NS_WARN_IF(!CycleCollectedJSContext::Get())) {
-    return NS_ERROR_UNEXPECTED;
-  }
-  nsContentUtils::RunInStableState(Move(aEvent));
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-StableStateEventTarget::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
-{
-  return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
-}
-
-NS_IMETHODIMP
-StableStateEventTarget::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aDelay)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
 } // namespace
 
 /**
@@ -777,9 +730,6 @@ nsContentUtils::Init()
 
   Unused << nsRFPService::GetOrCreate();
 
-  RefPtr<StableStateEventTarget> stableStateEventTarget = new StableStateEventTarget();
-  stableStateEventTarget.forget(&sStableStateEventTarget);
-
   nsCOMPtr<nsIUUIDGenerator> uuidGenerator =
     do_GetService("@mozilla.org/uuid-generator;1", &rv);
   if (NS_WARN_IF(NS_FAILED(rv))) {
@@ -2206,8 +2156,6 @@ nsContentUtils::Shutdown()
 
   NS_IF_RELEASE(sSameOriginChecker);
 
-  NS_IF_RELEASE(sStableStateEventTarget);
-
   if (sUserInteractionObserver) {
     sUserInteractionObserver->Shutdown();
     NS_RELEASE(sUserInteractionObserver);
@@ -5713,13 +5661,6 @@ nsContentUtils::RunInMetastableState(already_AddRefed<nsIRunnable> aRunnable)
   CycleCollectedJSContext::Get()->RunInMetastableState(Move(aRunnable));
 }
 
-/* static */
-nsISerialEventTarget*
-nsContentUtils::GetStableStateEventTarget()
-{
-  return sStableStateEventTarget;
-}
-
 void
 nsContentUtils::EnterMicroTask()
 {
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index da3b8c3ecb4d..ae3c5fd2ad18 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -1879,16 +1879,6 @@ public:
    */
   static void RunInMetastableState(already_AddRefed<nsIRunnable> aRunnable);
 
-  /**
-   * Returns a nsISerialEventTarget which will run any event dispatched to it
-   * once the event loop has reached a "stable state". Runnables dispatched to
-   * this event target must not cause any queued events to be processed (i.e.
-   * must not spin the event loop).
-   *
-   * See RunInStableState for more information about stable states
-   */
-  static nsISerialEventTarget* GetStableStateEventTarget();
-
   // Call EnterMicroTask when you're entering JS execution.
   // Usually the best way to do this is to use nsAutoMicroTask.
   static void EnterMicroTask();
@@ -3237,8 +3227,6 @@ private:
    */
   static bool sFragmentParsingActive;
 
-  static nsISerialEventTarget* sStableStateEventTarget;
-
   static nsString* sShiftText;
   static nsString* sControlText;
   static nsString* sMetaText;