diff --git a/dom/webidl/WorkerGlobalScope.webidl b/dom/webidl/WorkerGlobalScope.webidl
index ef61a18c1715..32648a8c526f 100644
--- a/dom/webidl/WorkerGlobalScope.webidl
+++ b/dom/webidl/WorkerGlobalScope.webidl
@@ -53,7 +53,6 @@ WorkerGlobalScope implements ImageBitmapFactories;
 
 // Mozilla extensions
 partial interface WorkerGlobalScope {
-  attribute EventHandler onclose;
 
   void dump(optional DOMString str);
 
diff --git a/dom/workers/RuntimeService.h b/dom/workers/RuntimeService.h
index 2de91c810a1b..2e5cc1dad581 100644
--- a/dom/workers/RuntimeService.h
+++ b/dom/workers/RuntimeService.h
@@ -215,18 +215,6 @@ public:
   void
   UpdateAllWorkerMemoryParameter(JSGCParamKey aKey, uint32_t aValue);
 
-  static uint32_t
-  GetContentCloseHandlerTimeoutSeconds()
-  {
-    return sDefaultJSSettings.content.maxScriptRuntime;
-  }
-
-  static uint32_t
-  GetChromeCloseHandlerTimeoutSeconds()
-  {
-    return sDefaultJSSettings.chrome.maxScriptRuntime;
-  }
-
 #ifdef JS_GC_ZEAL
   static void
   SetDefaultGCZeal(uint8_t aGCZeal, uint32_t aFrequency)
diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 1099cac9aa73..4680d560f861 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -603,64 +603,6 @@ private:
   }
 };
 
-class CloseEventRunnable final : public WorkerRunnable
-{
-public:
-  explicit CloseEventRunnable(WorkerPrivate* aWorkerPrivate)
-  : WorkerRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount)
-  { }
-
-private:
-  virtual bool
-  PreDispatch(WorkerPrivate* aWorkerPrivate) override
-  {
-    MOZ_CRASH("Don't call Dispatch() on CloseEventRunnable!");
-  }
-
-  virtual void
-  PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
-  {
-    MOZ_CRASH("Don't call Dispatch() on CloseEventRunnable!");
-  }
-
-  virtual bool
-  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
-  {
-    aWorkerPrivate->CloseHandlerStarted();
-
-    WorkerGlobalScope* globalScope = aWorkerPrivate->GlobalScope();
-
-    RefPtr<Event> event = NS_NewDOMEvent(globalScope, nullptr, nullptr);
-
-    event->InitEvent(NS_LITERAL_STRING("close"), false, false);
-    event->SetTrusted(true);
-
-    globalScope->DispatchDOMEvent(nullptr, event, nullptr, nullptr);
-
-    return true;
-  }
-
-  nsresult Cancel() override
-  {
-    // We need to run regardless.
-    Run();
-    return WorkerRunnable::Cancel();
-  }
-
-  virtual void
-  PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate, bool aRunResult)
-          override
-  {
-    // Report errors.
-    WorkerRunnable::PostRun(aCx, aWorkerPrivate, aRunResult);
-
-    // Match the busy count increase from NotifyRunnable.
-    aWorkerPrivate->ModifyBusyCountFromWorker(false);
-
-    aWorkerPrivate->CloseHandlerFinished();
-  }
-};
-
 class MessageEventRunnable final : public WorkerRunnable
                                  , public StructuredCloneHolder
 {
@@ -899,8 +841,6 @@ private:
   PreDispatch(WorkerPrivate* aWorkerPrivate) override
   {
     aWorkerPrivate->AssertIsOnParentThread();
-    // Modify here, but not in PostRun! This busy count addition will be matched
-    // by the CloseEventRunnable.
     return aWorkerPrivate->ModifyBusyCount(true);
   }
 
@@ -915,6 +855,14 @@ private:
     }
   }
 
+  virtual void
+  PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate, bool aRunResult)
+          override
+  {
+    aWorkerPrivate->ModifyBusyCountFromWorker(false);
+    return;
+  }
+
   virtual bool
   WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
   {
@@ -935,9 +883,7 @@ private:
   virtual bool
   WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
   {
-    // This busy count will be matched by the CloseEventRunnable.
-    return aWorkerPrivate->ModifyBusyCount(true) &&
-           aWorkerPrivate->Close();
+    return aWorkerPrivate->Close();
   }
 };
 
@@ -1356,111 +1302,6 @@ DummyCallback(nsITimer* aTimer, void* aClosure)
   // Nothing!
 }
 
-class KillCloseEventRunnable final : public WorkerRunnable
-{
-  nsCOMPtr<nsITimer> mTimer;
-
-  class KillScriptRunnable final : public WorkerControlRunnable
-  {
-  public:
-    explicit KillScriptRunnable(WorkerPrivate* aWorkerPrivate)
-    : WorkerControlRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount)
-    { }
-
-  private:
-    virtual bool
-    PreDispatch(WorkerPrivate* aWorkerPrivate) override
-    {
-      // Silence bad assertions, this is dispatched from the timer thread.
-      return true;
-    }
-
-    virtual void
-    PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
-    {
-      // Silence bad assertions, this is dispatched from the timer thread.
-    }
-
-    virtual bool
-    WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
-    {
-      // Kill running script.
-      return false;
-    }
-  };
-
-public:
-  explicit KillCloseEventRunnable(WorkerPrivate* aWorkerPrivate)
-  : WorkerRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount)
-  { }
-
-  bool
-  SetTimeout(uint32_t aDelayMS)
-  {
-    nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID);
-    if (!timer) {
-      return false;
-    }
-
-    RefPtr<KillScriptRunnable> runnable =
-      new KillScriptRunnable(mWorkerPrivate);
-
-    RefPtr<TimerThreadEventTarget> target =
-      new TimerThreadEventTarget(mWorkerPrivate, runnable);
-
-    if (NS_FAILED(timer->SetTarget(target))) {
-      return false;
-    }
-
-    if (NS_FAILED(timer->InitWithNamedFuncCallback(
-          DummyCallback, nullptr, aDelayMS, nsITimer::TYPE_ONE_SHOT,
-          "dom::workers::DummyCallback(1)"))) {
-      return false;
-    }
-
-    mTimer.swap(timer);
-    return true;
-  }
-
-private:
-  ~KillCloseEventRunnable()
-  {
-    if (mTimer) {
-      mTimer->Cancel();
-    }
-  }
-
-  virtual bool
-  PreDispatch(WorkerPrivate* aWorkerPrivate) override
-  {
-    MOZ_CRASH("Don't call Dispatch() on KillCloseEventRunnable!");
-  }
-
-  virtual void
-  PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
-  {
-    MOZ_CRASH("Don't call Dispatch() on KillCloseEventRunnable!");
-  }
-
-  virtual bool
-  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
-  {
-    if (mTimer) {
-      mTimer->Cancel();
-      mTimer = nullptr;
-    }
-
-    return true;
-  }
-
-  nsresult Cancel() override
-  {
-    // We need to run regardless.
-    Run();
-    return WorkerRunnable::Cancel();
-  }
-};
-
 class UpdateContextOptionsRunnable final : public WorkerControlRunnable
 {
   JS::ContextOptions mContextOptions;
@@ -4035,8 +3876,6 @@ WorkerPrivate::WorkerPrivate(WorkerPrivate* aParent,
   , mFrozen(false)
   , mTimerRunning(false)
   , mRunningExpiredTimeouts(false)
-  , mCloseHandlerStarted(false)
-  , mCloseHandlerFinished(false)
   , mPendingEventQueueClearing(false)
   , mMemoryReporterRunning(false)
   , mBlockedForMemoryReporter(false)
@@ -4258,7 +4097,6 @@ WorkerPrivate::GetLoadInfo(JSContext* aCx, nsPIDOMWindowInner* aWindow,
     }
 
     if (parentStatus > Running) {
-      NS_WARNING("Cannot create child workers from the close handler!");
       return NS_ERROR_FAILURE;
     }
 
@@ -4536,12 +4374,13 @@ WorkerPrivate::DoRunLoop(JSContext* aCx)
   Maybe<JSAutoCompartment> workerCompartment;
 
   for (;;) {
-    Status currentStatus;
+    Status currentStatus, previousStatus;
     bool debuggerRunnablesPending = false;
     bool normalRunnablesPending = false;
 
     {
       MutexAutoLock lock(mMutex);
+      previousStatus = mStatus;
 
       while (mControlQueue.IsEmpty() &&
              !(debuggerRunnablesPending = !mDebuggerQueue.IsEmpty()) &&
@@ -4562,10 +4401,11 @@ WorkerPrivate::DoRunLoop(JSContext* aCx)
       currentStatus = mStatus;
     }
 
-    // If the close handler has finished and all holders are done then we can
-    // kill this thread.
+    // if all holders are done then we can kill this thread.
     if (currentStatus != Running && !HasActiveHolders()) {
-      if (mCloseHandlerFinished && currentStatus != Killing) {
+
+      // If we just changed status, we must schedule the current runnables.
+      if (previousStatus != Running && currentStatus != Killing) {
         NotifyInternal(aCx, Killing);
         MOZ_ASSERT(!JS_IsExceptionPending(aCx));
 
@@ -4646,10 +4486,8 @@ WorkerPrivate::DoRunLoop(JSContext* aCx)
         JS_MaybeGC(aCx);
       }
     } else if (normalRunnablesPending) {
-      MOZ_ASSERT(NS_HasPendingEvents(mThread));
-
       // Process a single runnable from the main queue.
-      MOZ_ALWAYS_TRUE(NS_ProcessNextEvent(mThread, false));
+      NS_ProcessNextEvent(mThread, false);
 
       normalRunnablesPending = NS_HasPendingEvents(mThread);
       if (normalRunnablesPending && GlobalScope()) {
@@ -4851,7 +4689,7 @@ WorkerPrivate::InterruptCallback(JSContext* aCx)
         break;
       }
 
-      WaitForWorkerEvents(PR_MillisecondsToInterval(RemainingRunTimeMS()));
+      WaitForWorkerEvents(PR_MillisecondsToInterval(UINT32_MAX));
     }
   }
 
@@ -5153,17 +4991,6 @@ WorkerPrivate::ClearDebuggerEventQueue()
   }
 }
 
-uint32_t
-WorkerPrivate::RemainingRunTimeMS() const
-{
-  if (mKillTime.IsNull()) {
-    return UINT32_MAX;
-  }
-  TimeDuration runtime = mKillTime - TimeStamp::Now();
-  double ms = runtime > TimeDuration(0) ? runtime.ToMilliseconds() : 0;
-  return ms > double(UINT32_MAX) ? UINT32_MAX : uint32_t(ms);
-}
-
 bool
 WorkerPrivate::FreezeInternal()
 {
@@ -5802,8 +5629,6 @@ WorkerPrivate::NotifyInternal(JSContext* aCx, Status aStatus)
 
   MOZ_ASSERT(previousStatus != Pending);
 
-  MOZ_ASSERT(previousStatus >= Canceling || mKillTime.IsNull());
-
   // Let all our holders know the new status.
   NotifyHolders(aCx, aStatus);
   MOZ_ASSERT(!JS_IsExceptionPending(aCx));
@@ -5820,28 +5645,12 @@ WorkerPrivate::NotifyInternal(JSContext* aCx, Status aStatus)
     }
   }
 
-  // If we've run the close handler, we don't need to do anything else.
-  if (mCloseHandlerFinished) {
-    return true;
-  }
-
   // If the worker script never ran, or failed to compile, we don't need to do
-  // anything else, except pretend that we ran the close handler.
+  // anything else.
   if (!GlobalScope()) {
-    mCloseHandlerStarted = true;
-    mCloseHandlerFinished = true;
     return true;
   }
 
-  // If this is the first time our status has changed we also need to schedule
-  // the close handler unless we're being shut down.
-  if (previousStatus == Running && aStatus != Killing) {
-    MOZ_ASSERT(!mCloseHandlerStarted && !mCloseHandlerFinished);
-
-    RefPtr<CloseEventRunnable> closeRunnable = new CloseEventRunnable(this);
-    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToCurrentThread(closeRunnable));
-  }
-
   if (aStatus == Closing) {
     // Notify parent to stop sending us messages and balance our busy count.
     RefPtr<CloseRunnable> runnable = new CloseRunnable(this);
@@ -5853,60 +5662,14 @@ WorkerPrivate::NotifyInternal(JSContext* aCx, Status aStatus)
     return true;
   }
 
-  if (aStatus == Terminating) {
-    // Only abort the script if we're not yet running the close handler.
-    return mCloseHandlerStarted;
-  }
-
-  if (aStatus == Canceling) {
-    // We need to enforce a timeout on the close handler.
-    MOZ_ASSERT(previousStatus >= Running && previousStatus <= Terminating);
-
-    uint32_t killSeconds = IsChromeWorker() ?
-      RuntimeService::GetChromeCloseHandlerTimeoutSeconds() :
-      RuntimeService::GetContentCloseHandlerTimeoutSeconds();
-
-    if (killSeconds) {
-      mKillTime = TimeStamp::Now() + TimeDuration::FromSeconds(killSeconds);
-
-      if (!mCloseHandlerFinished && !ScheduleKillCloseEventRunnable()) {
-        return false;
-      }
-    }
-
-    // Only abort the script if we're not yet running the close handler.
-    return mCloseHandlerStarted;
-  }
-
-  MOZ_ASSERT(aStatus == Killing);
-
-  mKillTime = TimeStamp::Now();
-
-  if (mCloseHandlerStarted && !mCloseHandlerFinished) {
-    ScheduleKillCloseEventRunnable();
-  }
+  MOZ_ASSERT(aStatus == Terminating ||
+             aStatus == Canceling ||
+             aStatus == Killing);
 
   // Always abort the script.
   return false;
 }
 
-bool
-WorkerPrivate::ScheduleKillCloseEventRunnable()
-{
-  AssertIsOnWorkerThread();
-  MOZ_ASSERT(!mKillTime.IsNull());
-
-  RefPtr<KillCloseEventRunnable> killCloseEventRunnable =
-    new KillCloseEventRunnable(this);
-  if (!killCloseEventRunnable->SetTimeout(RemainingRunTimeMS())) {
-    return false;
-  }
-
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToCurrentThread(killCloseEventRunnable));
-
-  return true;
-}
-
 void
 WorkerPrivate::ReportError(JSContext* aCx, const char* aFallbackMessage,
                            JSErrorReport* aReport)
@@ -5965,9 +5728,8 @@ WorkerPrivate::ReportError(JSContext* aCx, const char* aFallbackMessage,
   mErrorHandlerRecursionCount++;
 
   // Don't want to run the scope's error handler if this is a recursive error or
-  // if there was an error in the close handler or if we ran out of memory.
+  // if we ran out of memory.
   bool fireAtScope = mErrorHandlerRecursionCount == 1 &&
-                     !mCloseHandlerStarted &&
                      errorNumber != JSMSG_OUT_OF_MEMORY &&
                      JS::CurrentGlobalOrNull(aCx);
 
@@ -6008,13 +5770,6 @@ WorkerPrivate::SetTimeout(JSContext* aCx,
     currentStatus = mStatus;
   }
 
-  // It's a script bug if setTimeout/setInterval are called from a close handler
-  // so throw an exception.
-  if (currentStatus == Closing) {
-    aRv.Throw(NS_ERROR_FAILURE);
-    return 0;
-  }
-
   // If the worker is trying to call setTimeout/setInterval and the parent
   // thread has initiated the close process then just silently fail.
   if (currentStatus >= Closing) {
diff --git a/dom/workers/WorkerPrivate.h b/dom/workers/WorkerPrivate.h
index 6f8c2615c8da..0a0e8e30d245 100644
--- a/dom/workers/WorkerPrivate.h
+++ b/dom/workers/WorkerPrivate.h
@@ -950,8 +950,6 @@ class WorkerPrivate : public WorkerPrivateParent<WorkerPrivate>
   bool mFrozen;
   bool mTimerRunning;
   bool mRunningExpiredTimeouts;
-  bool mCloseHandlerStarted;
-  bool mCloseHandlerFinished;
   bool mPendingEventQueueClearing;
   bool mMemoryReporterRunning;
   bool mBlockedForMemoryReporter;
@@ -1155,20 +1153,6 @@ public:
   bool
   RescheduleTimeoutTimer(JSContext* aCx);
 
-  void
-  CloseHandlerStarted()
-  {
-    AssertIsOnWorkerThread();
-    mCloseHandlerStarted = true;
-  }
-
-  void
-  CloseHandlerFinished()
-  {
-    AssertIsOnWorkerThread();
-    mCloseHandlerFinished = true;
-  }
-
   void
   UpdateContextOptionsInternal(JSContext* aCx, const JS::ContextOptions& aContextOptions);
 
@@ -1369,24 +1353,16 @@ private:
       status = mStatus;
     }
 
-    if (status >= Killing) {
-      return false;
+    if (status < Terminating) {
+      return true;
     }
-    if (status >= Running) {
-      return mKillTime.IsNull() || RemainingRunTimeMS() > 0;
-    }
-    return true;
-  }
 
-  uint32_t
-  RemainingRunTimeMS() const;
+    return false;
+  }
 
   void
   CancelAllTimeouts();
 
-  bool
-  ScheduleKillCloseEventRunnable();
-
   enum class ProcessAllControlRunnablesResult
   {
     // We did not process anything.
diff --git a/dom/workers/WorkerScope.h b/dom/workers/WorkerScope.h
index d0f9a800909d..56df9e4c3197 100644
--- a/dom/workers/WorkerScope.h
+++ b/dom/workers/WorkerScope.h
@@ -148,7 +148,6 @@ public:
 
   IMPL_EVENT_HANDLER(online)
   IMPL_EVENT_HANDLER(offline)
-  IMPL_EVENT_HANDLER(close)
 
   void
   Dump(const Optional<nsAString>& aString) const;
diff --git a/dom/workers/test/closeOnGC_server.sjs b/dom/workers/test/closeOnGC_server.sjs
deleted file mode 100644
index 55d0402a6afd..000000000000
--- a/dom/workers/test/closeOnGC_server.sjs
+++ /dev/null
@@ -1,23 +0,0 @@
-/**
- * Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-function handleRequest(request, response)
-{
-  response.setHeader("Content-Type", "text/plain", false);
-  response.setHeader("Cache-Control", "no-cache", false);
-
-  if (request.method == "POST") {
-    setState("seenPost" + request.queryString, "1");
-    return;
-  }
-
-  if (request.method == "GET") {
-    if (getState("seenPost" + request.queryString) == "1") {
-      response.write("closed");
-    }
-    return;
-  }
-
-  response.setStatusLine(request.httpVersion, 404, "Not found");
-}
diff --git a/dom/workers/test/closeOnGC_worker.js b/dom/workers/test/closeOnGC_worker.js
deleted file mode 100644
index 3d7f3edd2ab7..000000000000
--- a/dom/workers/test/closeOnGC_worker.js
+++ /dev/null
@@ -1,11 +0,0 @@
-/**
- * Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-onclose = function() {
-  var xhr = new XMLHttpRequest();
-  xhr.open("POST", "closeOnGC_server.sjs" + location.search, false);
-  xhr.send();
-};
-
-postMessage("ready");
diff --git a/dom/workers/test/close_worker.js b/dom/workers/test/close_worker.js
deleted file mode 100644
index 26714bfed6c7..000000000000
--- a/dom/workers/test/close_worker.js
+++ /dev/null
@@ -1,21 +0,0 @@
-/**
- * Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-onclose = function() {
-  postMessage("closed");
-  // Try to open a new worker.
-  try {
-    var worker = new Worker("close_worker.js");
-    throw new Error("We shouldn't get here!");
-  } catch (e) {
-    // pass
-  }
-};
-
-setTimeout(function () {
-  setTimeout(function () {
-    throw new Error("I should never run!");
-  }, 1000);
-  close();
-}, 1000);
diff --git a/dom/workers/test/mochitest.ini b/dom/workers/test/mochitest.ini
index 57625bc6da3f..d1ee29f58b1d 100644
--- a/dom/workers/test/mochitest.ini
+++ b/dom/workers/test/mochitest.ini
@@ -11,9 +11,6 @@ support-files =
   bug998474_worker.js
   bug1063538_worker.js
   clearTimeouts_worker.js
-  closeOnGC_server.sjs
-  closeOnGC_worker.js
-  close_worker.js
   content_worker.js
   console_worker.js
   consoleReplaceable_worker.js
@@ -146,8 +143,6 @@ skip-if = true # bug 1176225
 [test_bug1132924.html]
 [test_chromeWorker.html]
 [test_clearTimeouts.html]
-[test_close.html]
-[test_closeOnGC.html]
 [test_console.html]
 [test_consoleAndBlobs.html]
 [test_consoleReplaceable.html]
diff --git a/dom/workers/test/terminate_worker.js b/dom/workers/test/terminate_worker.js
index ad4e8252773d..f1a49e03266c 100644
--- a/dom/workers/test/terminate_worker.js
+++ b/dom/workers/test/terminate_worker.js
@@ -2,10 +2,6 @@
  * Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
-onclose = function() {
-  postMessage("Closed!");
-}
-
 onmessage = function(event) {
   throw "No messages should reach me!";
 }
diff --git a/dom/workers/test/test_close.html b/dom/workers/test/test_close.html
deleted file mode 100644
index 2fc546c416b7..000000000000
--- a/dom/workers/test/test_close.html
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--
-  Any copyright is dedicated to the Public Domain.
-  http://creativecommons.org/publicdomain/zero/1.0/
--->
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>Test for DOM Worker Threads</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-</head>
-<body>
-<p id="display"></p>
-<div id="content" style="display: none"></div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-
-  var worker = new Worker("close_worker.js");
-  worker.onmessage = function(event) {
-    is(event.data, "closed");
-    SimpleTest.finish();
-  }
-
-  SimpleTest.waitForExplicitFinish();
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/dom/workers/test/test_closeOnGC.html b/dom/workers/test/test_closeOnGC.html
deleted file mode 100644
index c1b8f83cef78..000000000000
--- a/dom/workers/test/test_closeOnGC.html
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--
-  Any copyright is dedicated to the Public Domain.
-  http://creativecommons.org/publicdomain/zero/1.0/
--->
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>Test for DOM Worker Threads</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-</head>
-<body>
-<p id="display"></p>
-<div id="content" style="display: none"></div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-
-  var count = 0;
-
-  function testWorker(queryString) {
-    ++count;
-    var worker = new Worker("closeOnGC_worker.js?" + queryString);
-    worker.onmessage = function(event) {
-      is(event.data, "ready");
-      worker = null;
-    }
-
-    var interval = setInterval(function() {
-      var xhr = new XMLHttpRequest();
-      xhr.open("GET", "closeOnGC_server.sjs?" + queryString, false);
-      xhr.send();
-      if (xhr.responseText != "closed") {
-        SpecialPowers.gc();
-        return;
-      }
-      clearInterval(interval);
-      ok(true, "xhr correctly closed");
-      if (--count == 0) {
-        SimpleTest.finish();
-      }
-    }, 500);
-
-    return worker;
-  }
-
-  testWorker("white");
-  var worker = testWorker("gray");
-  worker.onerror = function() {};
-  worker.onerror.foo = worker;
-  worker = null;
-
-  SimpleTest.waitForExplicitFinish();
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/dom/workers/test/test_terminate.html b/dom/workers/test/test_terminate.html
index 0d060dc58b42..5d31bd16523a 100644
--- a/dom/workers/test/test_terminate.html
+++ b/dom/workers/test/test_terminate.html
@@ -30,7 +30,7 @@ Tests of DOM Worker terminate feature
 
   function messageListener(event) {
     is(event.data, "Still alive!", "Correct message!");
-    if (messageCount++ == 20) {
+    if (++messageCount == 20) {
       ok(worker.onmessage === messageListener,
          "Correct listener before terminate");
 
@@ -82,7 +82,7 @@ Tests of DOM Worker terminate feature
   }
 
   function testCount() {
-    is(messageCount, 21, "Received another message after terminated!");
+    is(messageCount, 20, "Received another message after terminated!");
     if (intervalCount++ == 5) {
       clearInterval(interval);
       SimpleTest.finish();
diff --git a/toolkit/modules/subprocess/subprocess_worker_common.js b/toolkit/modules/subprocess/subprocess_worker_common.js
index 095bb6fb9ae2..2b681e737884 100644
--- a/toolkit/modules/subprocess/subprocess_worker_common.js
+++ b/toolkit/modules/subprocess/subprocess_worker_common.js
@@ -227,9 +227,3 @@ onmessage = event => {
     });
   });
 };
-
-onclose = event => {
-  io.shutdown();
-
-  self.postMessage({msg: "close"});
-};
diff --git a/toolkit/modules/subprocess/subprocess_worker_unix.js b/toolkit/modules/subprocess/subprocess_worker_unix.js
index 1a2595c286fb..1a6118707536 100644
--- a/toolkit/modules/subprocess/subprocess_worker_unix.js
+++ b/toolkit/modules/subprocess/subprocess_worker_unix.js
@@ -500,6 +500,7 @@ io = {
       this.signal.cleanup();
       this.signal = null;
 
+      self.postMessage({msg: "close"});
       self.close();
     }
   },
diff --git a/toolkit/modules/subprocess/subprocess_worker_win.js b/toolkit/modules/subprocess/subprocess_worker_win.js
index a12dd83ff9e4..b0756dac344e 100644
--- a/toolkit/modules/subprocess/subprocess_worker_win.js
+++ b/toolkit/modules/subprocess/subprocess_worker_win.js
@@ -599,6 +599,7 @@ io = {
       this.signal.cleanup();
       this.signal = null;
 
+      self.postMessage({msg: "close"});
       self.close();
     }
   },