Store constant variable initializers in elements.

pkg/compiler/lib/src/mirrors/dart2js_mirrors.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 dart2js.mirrors;
 
 import 'dart:collection' show UnmodifiableListView, UnmodifiableMapView;
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
@@ skipping 445 matching lines @@
         .mapToList((cu) => new Dart2JsCompilationUnitMirror(cu, library));
   }
 
   static Iterable<ConstantExpression> metadataSyntaxOf(
       Dart2JsElementMirror declaration) {
     return declaration._element.metadata.map((metadata) => metadata.constant);
   }
 
   static ConstantExpression initializerSyntaxOf(Dart2JsFieldMirror variable) {
     Compiler compiler = variable.mirrorSystem.compiler;
-    return compiler.constants.getConstantForVariable(variable._variable);
+    return variable._variable.constant;
   }
 
   static ConstantExpression defaultValueSyntaxOf(
       Dart2JsParameterMirror parameter) {
     if (!parameter.hasDefaultValue) return null;
     ParameterElement parameterElement = parameter._element;
     Compiler compiler = parameter.mirrorSystem.compiler;
-    return compiler.constants.getConstantForVariable(parameterElement);
+    return parameterElement.constant;
   }
 
   static Mirror getMirrorFromElement(Dart2JsMirror mirror, Element element) {
     return _convertElementToDeclarationMirror(mirror.mirrorSystem, element);
   }
 }