diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 22e2608bab3..67620219915 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -55,6 +55,7 @@
 #include "nsIURI.h"
 #include "nsIURL.h"
 #include "nsIXPConnect.h"
+#include "nsIXPCScriptNotify.h"
 
 #include "jsfriendapi.h"
 #include "jsdbgapi.h"
@@ -966,6 +967,13 @@ public:
     bool dummy;
     return DispatchEventToTarget(aCx, target, event, &dummy);
   }
+
+  void PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate, bool aRunResult)
+  {
+    // Notify before WorkerRunnable::PostRun, since that can kill aWorkerPrivate
+    NotifyScriptExecutedIfNeeded();
+    WorkerRunnable::PostRun(aCx, aWorkerPrivate, aRunResult);
+  }
 };
 
 class NotifyRunnable : public WorkerControlRunnable
@@ -1111,6 +1119,13 @@ public:
                                             mErrorNumber, innerWindowId);
   }
 
+  void PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate, bool aRunResult)
+  {
+    // Notify before WorkerRunnable::PostRun, since that can kill aWorkerPrivate
+    NotifyScriptExecutedIfNeeded();
+    WorkerRunnable::PostRun(aCx, aWorkerPrivate, aRunResult);
+  }
+
   static bool
   ReportError(JSContext* aCx, WorkerPrivate* aWorkerPrivate,
               bool aFireAtScope, JSObject* aTarget, const nsString& aMessage,
@@ -1816,6 +1831,18 @@ WorkerRunnable::PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate,
   }
 }
 
+void
+WorkerRunnable::NotifyScriptExecutedIfNeeded() const
+{
+  // if we're on the main thread notify about the end of our script execution.
+  if (mTarget == ParentThread && !mWorkerPrivate->GetParent()) {
+    AssertIsOnMainThread();
+    if (mWorkerPrivate->GetScriptNotify()) {
+      mWorkerPrivate->GetScriptNotify()->ScriptExecuted();
+    }
+  }
+}
+
 struct WorkerPrivate::TimeoutInfo
 {
   TimeoutInfo()
@@ -1881,6 +1908,7 @@ WorkerPrivateParent<Derived>::WorkerPrivateParent(
 
   mWindow.swap(aWindow);
   mScriptContext.swap(aScriptContext);
+  mScriptNotify = do_QueryInterface(mScriptContext);
   mBaseURI.swap(aBaseURI);
   mPrincipal.swap(aPrincipal);
   mDocument.swap(aDocument);
@@ -2181,10 +2209,11 @@ WorkerPrivateParent<Derived>::ForgetMainThreadObjects(
   AssertIsOnParentThread();
   MOZ_ASSERT(!mMainThreadObjectsForgotten);
 
-  aDoomed.SetCapacity(6);
+  aDoomed.SetCapacity(7);
 
   SwapToISupportsArray(mWindow, aDoomed);
   SwapToISupportsArray(mScriptContext, aDoomed);
+  SwapToISupportsArray(mScriptNotify, aDoomed);
   SwapToISupportsArray(mBaseURI, aDoomed);
   SwapToISupportsArray(mScriptURI, aDoomed);
   SwapToISupportsArray(mPrincipal, aDoomed);
diff --git a/dom/workers/WorkerPrivate.h b/dom/workers/WorkerPrivate.h
index 9c9716e4c3e..b4c7b24d7bb 100644
--- a/dom/workers/WorkerPrivate.h
+++ b/dom/workers/WorkerPrivate.h
@@ -69,6 +69,7 @@ class nsIScriptContext;
 class nsIURI;
 class nsPIDOMWindow;
 class nsITimer;
+class nsIXPCScriptNotify;
 
 BEGIN_WORKERS_NAMESPACE
 
@@ -133,6 +134,8 @@ protected:
   virtual void
   PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate, bool aRunResult);
 
+  void NotifyScriptExecutedIfNeeded() const;
+
 private:
   NS_DECL_NSIRUNNABLE
 };
@@ -207,6 +210,7 @@ private:
   // Main-thread things.
   nsCOMPtr<nsPIDOMWindow> mWindow;
   nsCOMPtr<nsIScriptContext> mScriptContext;
+  nsCOMPtr<nsIXPCScriptNotify> mScriptNotify;
   nsCOMPtr<nsIURI> mBaseURI;
   nsCOMPtr<nsIURI> mScriptURI;
   nsCOMPtr<nsIPrincipal> mPrincipal;
@@ -386,6 +390,13 @@ public:
     return mScriptContext;
   }
 
+  nsIXPCScriptNotify*
+  GetScriptNotify() const
+  {
+    AssertIsOnMainThread();
+    return mScriptNotify;
+  }
+
   JSObject*
   GetJSObject() const
   {