Inject a prototype object of a private script into the prototype chain of a holder object

Source/core/html/HTMLMarqueeElement.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
-installClass('HTMLMarqueeElement', function(global) {
+installClass('HTMLMarqueeElement', function(global, HTMLMarqueeElementPrototype) {
 
     var kDefaultScrollAmount = 6;
     var kDefaultScrollDelayMS = 85;
     var kMinimumScrollDelayMS = 60;
 
     var kDefaultLoopLimit = -1;
 
     var kBehaviorScroll = 'scroll';
     var kBehaviorSlide = 'slide';
     var kBehaviorAlternate = 'alternate';
@@ skipping 82 matching lines @@
                 // inline event handler.
                 var newEventHandler = value ? function() { value.apply(this, arguments) } : null;
                 if (newEventHandler)
                     this.addEventListener(eventName, newEventHandler);
                 this[functionPropertyName] = value;
                 this[eventHandlerPropertyName] = newEventHandler;
             },
         });
     }
 
-    var HTMLMarqueeElementPrototype = Object.create(HTMLElement.prototype);
-
     reflectAttribute(HTMLMarqueeElementPrototype, 'behavior', 'behavior');
     reflectAttribute(HTMLMarqueeElementPrototype, 'bgcolor', 'bgColor');
     reflectAttribute(HTMLMarqueeElementPrototype, 'direction', 'direction');
     reflectAttribute(HTMLMarqueeElementPrototype, 'height', 'height');
     reflectAttribute(HTMLMarqueeElementPrototype, 'hspace', 'hspace');
     reflectAttribute(HTMLMarqueeElementPrototype, 'vspace', 'vspace');
     reflectAttribute(HTMLMarqueeElementPrototype, 'width', 'width');
     reflectBooleanAttribute(HTMLMarqueeElementPrototype, 'truespeed', 'trueSpeed');
 
     defineInlineEventHandler(HTMLMarqueeElementPrototype, 'start');
@@ skipping 296 matching lines @@
             this.player_ = null;
             player.cancel();
         }
     };
 
     // FIXME: We have to inject this HTMLMarqueeElement as a custom element in order to make
     // createdCallback, attachedCallback, detachedCallback and attributeChangedCallback workable.
     // global.document.registerElement('i-marquee', {
     //    prototype: HTMLMarqueeElementPrototype,
     // });
-
-    return HTMLMarqueeElementPrototype;
 });