--- a/dom/workers/RuntimeService.cpp
+++ b/dom/workers/RuntimeService.cpp
@@ -1728,25 +1728,16 @@ RuntimeService::Init()
                                     PREF_MAX_SCRIPT_RUN_TIME_CHROME, -1))) {
     NS_WARNING("Failed to register timeout cache!");
   }
 
   int32_t maxPerDomain = Preferences::GetInt(PREF_WORKERS_MAX_PER_DOMAIN,
                                              MAX_WORKERS_PER_DOMAIN);
   gMaxWorkersPerDomain = std::max(0, maxPerDomain);
 
-  mDetectorName = Preferences::GetLocalizedCString("intl.charset.detector");
-
-  nsCOMPtr<nsIPlatformCharset> platformCharset =
-    do_GetService(NS_PLATFORMCHARSET_CONTRACTID, &rv);
-  if (NS_SUCCEEDED(rv)) {
-    rv = platformCharset->GetCharset(kPlatformCharsetSel_PlainTextInFile,
-                                     mSystemCharset);
-  }
-
   rv = InitOSFileConstants();
   if (NS_FAILED(rv)) {
     return rv;
   }
 
   return NS_OK;
 }
 

--- a/dom/workers/RuntimeService.h
+++ b/dom/workers/RuntimeService.h
@@ -91,19 +91,16 @@ private:
 
   // *Not* protected by mMutex.
   nsClassHashtable<nsPtrHashKey<nsPIDOMWindow>,
                    nsTArray<WorkerPrivate*> > mWindowMap;
 
   // Only used on the main thread.
   nsCOMPtr<nsITimer> mIdleThreadTimer;
 
-  nsCString mDetectorName;
-  nsCString mSystemCharset;
-
   static JSSettings sDefaultJSSettings;
   static bool sDefaultPreferences[WORKERPREF_COUNT];
 
 public:
   struct NavigatorStrings
   {
     nsString mAppName;
     nsString mAppVersion;
@@ -148,28 +145,16 @@ public:
   CreateSharedWorker(const GlobalObject& aGlobal,
                      const nsAString& aScriptURL,
                      const nsAString& aName,
                      SharedWorker** aSharedWorker);
 
   void
   ForgetSharedWorker(WorkerPrivate* aWorkerPrivate);
 
-  const nsACString&
-  GetDetectorName() const
-  {
-    return mDetectorName;
-  }
-
-  const nsACString&
-  GetSystemCharset() const
-  {
-    return mSystemCharset;
-  }
-
   const NavigatorStrings&
   GetNavigatorStrings() const
   {
     return mNavigatorStrings;
   }
 
   void
   NoteIdleThread(WorkerThread* aThread);