Implement subtype for type variables.

sdk/lib/_internal/compiler/implementation/mirrors/dart2js_mirror.dart

 // Copyright (c) 2012, 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.
 
 library mirrors_dart2js;
 
 import 'dart:async';
 import 'dart:collection' show LinkedHashMap;
 import 'dart:io';
 import 'dart:uri';
@@ skipping 1141 matching lines @@
   }
 
   LibraryMirror get library => declarer.library;
 
   DeclarationMirror get owner => declarer;
 
   bool get isTypeVariable => true;
 
   TypeMirror get upperBound => _convertTypeToTypeMirror(
       mirrors,
-      _typeVariableType.element.bound,
+      _typeVariableType.element.upperBound,
       mirrors.compiler.objectClass.computeType(mirrors.compiler));
 
   bool operator ==(Object other) {
     if (identical(this, other)) {
       return true;
     }
     if (other is! TypeVariableMirror) {
       return false;
     }
     if (declarer != other.declarer) {
@@ skipping 684 matching lines @@
       return new Future.immediate(
           new Dart2JsStringConstantMirror.fromString(mirrors, text));
     } else if (fieldName == 'trimmedText') {
       return new Future.immediate(
           new Dart2JsStringConstantMirror.fromString(mirrors, trimmedText));
     }
     // TODO(johnniwinther): Which exception/error should be thrown here?
     throw new UnsupportedError('InstanceMirror does not have a reflectee');
   }
 }