Issue 4353 - Remove deprecated __proto__ syntax

chrome/content/common.js

 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cr = Components.results;
 const Cu = Components.utils;
 
 const MILLIS_IN_SECOND = 1000;
 const MILLIS_IN_MINUTE = 60 * MILLIS_IN_SECOND;
 const MILLIS_IN_HOUR = 60 * MILLIS_IN_MINUTE;
 const MILLIS_IN_DAY = 24 * MILLIS_IN_HOUR;
 
@@ skipping 60 matching lines @@
   this._backup = {
     subscriptions: FilterStorage.subscriptions,
     storageKnown: FilterStorage.knownSubscriptions,
     subscriptionsKnown: Subscription.knownSubscriptions,
     filtersKnown: Filter.knownFilters,
     listeners: FilterNotifierGlobal.listeners,
     sourceFile: FilterStorage.sourceFile
   };
 
   FilterStorage.subscriptions = [];
-  FilterStorage.knownSubscriptions = {__proto__: null};
-  Subscription.knownSubscriptions = {__proto__: null};
-  Filter.knownFilters = {__proto__: null};
+  FilterStorage.knownSubscriptions = Object.create(null);
+  Subscription.knownSubscriptions = Object.create(null);
+  Filter.knownFilters = Object.create(null);
   if (!keepListeners)
   {
     FilterNotifierGlobal.listeners = [];
   }
 
   defaultMatcher.clear();
   ElemHide.clear();
   CSSRules.clear();
 }
 
@@ skipping 23 matching lines @@
   QUnit.done = function()
   {
     FilterNotifier.triggerListeners("load");
     return origDone.apply(this, arguments);
   };
   reinitScheduled = true;
 }
 
 function preparePrefs()
 {
-  this._pbackup = {__proto__: null};
+  this._pbackup = Object.create(null);
   for (let pref in Prefs)
   {
     if (Prefs.__lookupSetter__(pref))
       this._pbackup[pref] = Prefs[pref];
   }
   Prefs.enabled = true;
 }
 
 function restorePrefs()
 {
@@ skipping 17 matching lines @@
     // Replace Date.now() function
     this["_origNow" + module] = global.Date.now;
     global.Date.now = function() currentTime;
   }
 
   // Wrap timers
   if (processTimers)
   {
     processTimers(function wrapTimer(timer)
     {
-      let wrapper = {__proto__: timer};
+      let wrapper = Object.create(timer);
       let callback = timer.callback;
       wrapper.handler = function() callback.notify(wrapper);
       wrapper.nextExecution = currentTime + timer.delay;
       scheduledTasks.push(wrapper);
       timer.cancel();
       return wrapper;
     });
   }
 
   // Register observer to track outstanding requests
@@ skipping 351 matching lines @@
     return oldFinish.apply(this, arguments);
   }
   window.addEventListener("unload", function()
   {
     debuggerService.off();
   }, true);
   debuggerService.on();
   debuggerService.flags |= debuggerService.COLLECT_PROFILE_DATA;
   debuggerService.clearProfileData();
 }