Use ConstExp for storing constants.

sdk/lib/_internal/compiler/implementation/native_handler.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 native;
 
 import 'dart:collection' show Queue;
 import 'dart2jslib.dart';
 import 'dart_types.dart';
 import 'elements/elements.dart';
@@ skipping 314 matching lines @@
 
   /// Returns the JSName annotation string or `null` if no JSName annotation is
   /// present.
   String findJsNameFromAnnotation(Element element) {
     String name = null;
     ClassElement annotationClass = annotationJsNameClass;
     for (Link<MetadataAnnotation> link = element.metadata;
          !link.isEmpty;
          link = link.tail) {
       MetadataAnnotation annotation = link.head.ensureResolved(compiler);
-      var value = annotation.value;
+      var value = annotation.constant;
       if (value is! ConstructedConstant) continue;
       if (value.type is! InterfaceType) continue;
       if (!identical(value.type.element, annotationClass)) continue;
 
       var fields = value.fields;
       // TODO(sra): Better validation of the constant.
       if (fields.length != 1 || fields[0] is! StringConstant) {
         PartialMetadataAnnotation partial = annotation;
         compiler.internalError(annotation,
             'Annotations needs one string: ${partial.parseNode(compiler)}');
@@ skipping 744 matching lines @@
    * [annotationClass].
    * Returns `null` if no constraints.
    */
   static _collect(Element element, Compiler compiler, Element annotationClass,
                   lookup(str)) {
     var types = null;
     for (Link<MetadataAnnotation> link = element.metadata;
          !link.isEmpty;
          link = link.tail) {
       MetadataAnnotation annotation = link.head.ensureResolved(compiler);
-      var value = annotation.value;
+      var value = annotation.constant;
       if (value is! ConstructedConstant) continue;
       if (value.type is! InterfaceType) continue;
       if (!identical(value.type.element, annotationClass)) continue;
 
       var fields = value.fields;
       // TODO(sra): Better validation of the constant.
       if (fields.length != 1 || fields[0] is! StringConstant) {
         PartialMetadataAnnotation partial = annotation;
         compiler.internalError(annotation,
             'Annotations needs one string: ${partial.parseNode(compiler)}');
@@ skipping 222 matching lines @@
     LiteralString jsCode = nativeBody.asLiteralString();
     builder.push(new HForeign.statement(
         js.js.statementTemplateYielding(
             new js.LiteralStatement(jsCode.dartString.slowToString())),
         <HInstruction>[],
         new SideEffects(),
         null,
         backend.dynamicType));
   }
 }