Create local alias for super class in --closure mode (issue #312)

tool/input_sdk/private/types.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This library defines the representation of runtime types.
 part of dart._runtime;
 
 /// The Symbol for storing type arguments on a specialized generic type.
 final _mixins = JS('', 'Symbol("mixins")');
 @JSExportName('implements')
@@ skipping 20 matching lines @@
 /// Function types are represented in one of two ways:
 ///   - As an instance of FunctionType.  These are eagerly computed.
 ///   - As an instance of TypeDef.  The TypeDef representation lazily
 ///     computes an instance of FunctionType, and delegates to that instance.
 ///
 /// All types satisfy the following interface:
 ///  get String name;
 ///  String toString();
 ///
 ///
+final _TypeRepBase = JS('', '$LazyTagged(() => $Type)');
 final TypeRep = JS('', '''
-  class TypeRep extends $LazyTagged(() => $Type) {
+  class TypeRep extends $_TypeRepBase {
     get name() {return this.toString();}
   }
 ''');
 
 final Dynamic = JS('', '''
   class Dynamic extends $TypeRep {
     toString() { return "dynamic"; }
   }
 ''');
 @JSExportName('dynamic')
@@ skipping 483 matching lines @@
     return true;
   }
 
   let typeArgs = $getGenericArgs($type);
   if (!typeArgs) return true;
   for (let t of typeArgs) {
     if (t != $Object && t != $dynamicR) return false;
   }
   return true;
 })()''');