Fix Array constructor bug impacting dart2js and ddc running on the same page.

lib/runtime/dart/core.js

 var core;
 (function(exports) {
   'use strict';
   class Object {
     constructor() {
       let name = this.constructor.name;
       let init = this[name];
       let result = void 0;
       if (init)
         result = init.apply(this, arguments);
@@ skipping 1598 matching lines @@
         return new (_internal.IterableMixinWorkaround$(E))().asMapList(this);
       }
     }
     List[dart.implements] = () => [Iterable$(E), _internal.EfficientLength];
     dart.defineNamedConstructor(List, 'filled');
     dart.defineNamedConstructor(List, 'from');
     dart.defineNamedConstructor(List, 'generate');
     return List;
   });
   let List = List$();
-  dart.copyProperties(dart.global.Array.prototype, List.prototype);
+  dart.registerExtension(dart.global.Array, List);
   let Map$ = dart.generic(function(K, V) {
     class Map extends Object {
       Map() {
         return new (collection.LinkedHashMap$(K, V))();
       }
       from(other) {
         return new collection.LinkedHashMap$(K, V).from(other);
       }
       identity() {
         return new collection.LinkedHashMap$(K, V).identity();
@@ skipping 1895 matching lines @@
   exports.StackTrace = StackTrace;
   exports.Stopwatch = Stopwatch;
   exports.String = String;
   exports.RuneIterator = RuneIterator;
   exports.StringBuffer = StringBuffer;
   exports.StringSink = StringSink;
   exports.Symbol = Symbol;
   exports.Type = Type;
   exports.Uri = Uri;
 })(core || (core = {}));