Introduce TypedefEntity

pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart

 // Copyright (c) 2014, 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 dart2js.js_emitter.program_builder;
 
 import 'dart:io';
 import 'dart:convert' show JSON;
 
 import '../../closure.dart' show ClosureConversionTask, ClosureFieldElement;
 import '../../common.dart';
 import '../../common/names.dart' show Names, Selectors;
 import '../../constants/values.dart'
     show ConstantValue, InterceptorConstantValue;
 import '../../common_elements.dart' show CommonElements, ElementEnvironment;
 import '../../deferred_load.dart' show DeferredLoadTask, OutputUnit;
 import '../../elements/elements.dart'
     show
         ClassElement,
-        Elements,
         FieldElement,
         FunctionSignature,
         GetterElement,
         LibraryElement,
         MemberElement,
         MethodElement,
-        ParameterElement,
-        TypedefElement;
+        ParameterElement;
 import '../../elements/entities.dart';
 import '../../elements/resolution_types.dart'
     show ResolutionDartType, ResolutionFunctionType, ResolutionTypedefType;
 import '../../elements/types.dart' show DartType, DartTypes;
 import '../../js/js.dart' as js;
 import '../../js_backend/backend.dart' show SuperMemberData;
 import '../../js_backend/backend_usage.dart';
 import '../../js_backend/constant_handler_javascript.dart'
     show JavaScriptConstantCompiler;
 import '../../js_backend/custom_elements_analysis.dart';
@@ skipping 1154 matching lines @@
       Constant constant = new Constant(name, holder, constantValue);
       _constants[constantValue] = constant;
     }
   }
 
   Holder _registerStaticStateHolder() {
     return _registry.registerHolder(_namer.staticStateHolder,
         isStaticStateHolder: true);
   }
 }