Pass data objects to ConstantEmitter

pkg/compiler/lib/src/common_elements.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.
 
 // TODO(sigmund): rename and move to common/elements.dart
 library dart2js.type_system;
 
 import 'common/names.dart' show Identifiers, Uris;
 import 'constants/values.dart';
 import 'elements/entities.dart';
@@ skipping 721 matching lines @@
       _jsStringSplit ??= _findClassMember(jsStringClass, 'split');
 
   FunctionEntity _jsStringToString;
   FunctionEntity get jsStringToString =>
       _jsStringToString ??= _findClassMember(jsStringClass, 'toString');
 
   FunctionEntity _jsStringOperatorAdd;
   FunctionEntity get jsStringOperatorAdd =>
       _jsStringOperatorAdd ??= _findClassMember(jsStringClass, '+');
 
+  ClassEntity _jsConstClass;
+  ClassEntity get jsConstClass =>
+      _jsConstClass ??= _findClass(foreignLibrary, 'JS_CONST');
+
   // From package:js
   ClassEntity _jsAnnotationClass;
   ClassEntity get jsAnnotationClass {
     if (_jsAnnotationClass == null) {
       LibraryEntity library = _env.lookupLibrary(Uris.package_js);
       if (library == null) return null;
       _jsAnnotationClass = _findClass(library, 'JS');
     }
     return _jsAnnotationClass;
   }
@@ skipping 509 matching lines @@
   /// arguments, both required and optional.
   CallStructure getCallStructure(FunctionEntity entity);
 
   /// Returns `true` if [member] a the synthetic getter `loadLibrary` injected
   /// on deferred libraries.
   bool isDeferredLoadLibraryGetter(MemberEntity member);
 
   /// Returns the metadata constants declared on [member].
   Iterable<ConstantValue> getMemberMetadata(MemberEntity member);
 }