Revert "This is a speculative chain of reverts to improve a Chrome"

src/debug/mirrors.js

 // Copyright 2006-2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 "use strict";
 
 // ----------------------------------------------------------------------------
 // Imports
 
 var GlobalArray = global.Array;
 var IsNaN = global.isNaN;
 var JSONStringify = global.JSON.stringify;
-var MapEntries;
-var MapIteratorNext;
-var SetIteratorNext;
-var SetValues;
-
-utils.Import(function(from) {
-  MapEntries = from.MapEntries;
-  MapIteratorNext = from.MapIteratorNext;
-  SetIteratorNext = from.SetIteratorNext;
-  SetValues = from.SetValues;
-});
+var MapEntries = global.Map.prototype.entries;
+var MapIteratorNext = (new global.Map).entries().next;
+var SetIteratorNext = (new global.Set).values().next;
+var SetValues = global.Set.prototype.values;
 
 // ----------------------------------------------------------------------------
 
 // Mirror hierarchy:
 // - Mirror
 //   - ValueMirror
 //     - UndefinedMirror
 //     - NullMirror
 //     - BooleanMirror
 //     - NumberMirror
@@ skipping 2366 matching lines @@
   "GeneratorMirror", GeneratorMirror,
   "PropertyMirror", PropertyMirror,
   "InternalPropertyMirror", InternalPropertyMirror,
   "FrameMirror", FrameMirror,
   "ScriptMirror", ScriptMirror,
   "ScopeMirror", ScopeMirror,
   "FrameDetails", FrameDetails,
 ]);
 
 })