Introduce ClassLike, MemberLike, FieldLike and FunctionLike

pkg/compiler/lib/src/js_backend/backend.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 js_backend.backend;
 
 import 'dart:async' show Future;
 
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
 
@@ skipping 316 matching lines @@
 
   FunctionInlineCache inlineCache = new FunctionInlineCache();
 
   /// If [true], the compiler will emit code that logs whenever a method is
   /// called. When TRACE_METHOD is 'console' this will be logged
   /// directly in the JavaScript console. When TRACE_METHOD is 'post' the
   /// information will be sent to a server via a POST request.
   static const String TRACE_METHOD = const String.fromEnvironment('traceCalls');
   static const bool TRACE_CALLS =
       TRACE_METHOD == 'post' || TRACE_METHOD == 'console';
-  Element traceHelper;
+  MethodElement traceHelper;
 
   TypeMask get stringType => compiler.commonMasks.stringType;
   TypeMask get doubleType => compiler.commonMasks.doubleType;
   TypeMask get intType => compiler.commonMasks.intType;
   TypeMask get uint32Type => compiler.commonMasks.uint32Type;
   TypeMask get uint31Type => compiler.commonMasks.uint31Type;
   TypeMask get positiveIntType => compiler.commonMasks.positiveIntType;
   TypeMask get numType => compiler.commonMasks.numType;
   TypeMask get boolType => compiler.commonMasks.boolType;
   TypeMask get dynamicType => compiler.commonMasks.dynamicType;
@@ skipping 2940 matching lines @@
   ClassElement get mapImplementation => helpers.mapLiteralClass;
   ClassElement get constMapImplementation => helpers.constMapLiteralClass;
   ClassElement get typeImplementation => helpers.typeLiteralClass;
   ClassElement get boolImplementation => helpers.jsBoolClass;
   ClassElement get nullImplementation => helpers.jsNullClass;
   ClassElement get syncStarIterableImplementation => helpers.syncStarIterable;
   ClassElement get asyncFutureImplementation => helpers.futureImplementation;
   ClassElement get asyncStarStreamImplementation => helpers.controllerStream;
   ClassElement get functionImplementation => helpers.coreClasses.functionClass;
 }