Issue 4576 - Reinstate FilterStorage read/write integration test and test with please_kill_startup…

chrome/content/common.js

 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cr = Components.results;
 const Cu = Components.utils;
 
 const {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
 
 const SDK = Cu.import("resource://gre/modules/commonjs/toolkit/require.js", {});
 SDK.require("sdk/tabs");
 
@@ skipping 47 matching lines @@
 
   this._backup = {
     subscriptions: FilterStorage.subscriptions,
     storageKnown: FilterStorage.knownSubscriptions,
     subscriptionsKnown: Subscription.knownSubscriptions,
     filtersKnown: Filter.knownFilters,
     listeners: FilterNotifierGlobal.listeners,
     sourceFile: FilterStorage.sourceFile
   };
 
+  FilterStorage._loading = false;
   FilterStorage.subscriptions = [];
   FilterStorage.knownSubscriptions = Object.create(null);
   Subscription.knownSubscriptions = Object.create(null);
   Filter.knownFilters = Object.create(null);
   if (!keepListeners)
   {
     FilterNotifierGlobal.listeners = [];
   }
 
   defaultMatcher.clear();
@@ skipping 142 matching lines @@
     return oldFinish.apply(this, arguments);
   }
   window.addEventListener("unload", function()
   {
     debuggerService.off();
   }, true);
   debuggerService.on();
   debuggerService.flags |= debuggerService.COLLECT_PROFILE_DATA;
   debuggerService.clearProfileData();
 }