Refactor ConstantExpression/ConstantConstructor to use entities.

pkg/compiler/lib/src/resolution/resolution.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.resolution;
 
 import 'dart:collection' show Queue;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
@@ skipping 1065 matching lines @@
                   visitorFor(context, useEnclosingScope: true);
               ResolutionRegistry registry = visitor.registry;
               node.accept(visitor);
               // TODO(johnniwinther): Avoid passing the [TreeElements] to
               // [compileMetadata].
               ConstantExpression constant = constantCompiler.compileMetadata(
                   annotation, node, registry.mapping);
               switch (constant.kind) {
                 case ConstantExpressionKind.CONSTRUCTED:
                   ConstructedConstantExpression constructedConstant = constant;
-                  if (constructedConstant.type.isGeneric &&
-                      !constructedConstant.type.isRaw) {
+                  ResolutionInterfaceType type = constructedConstant.type;
+                  if (type.isGeneric && !type.isRaw) {
                     // Const constructor calls cannot have type arguments.
                     // TODO(24312): Remove this.
                     reporter.reportErrorMessage(
                         node, MessageKind.INVALID_METADATA_GENERIC);
                     constant = new ErroneousConstantExpression();
                   }
                   break;
-                case ConstantExpressionKind.VARIABLE:
+                case ConstantExpressionKind.FIELD:
                 case ConstantExpressionKind.ERRONEOUS:
                   break;
                 default:
                   reporter.reportErrorMessage(
                       node, MessageKind.INVALID_METADATA);
                   constant = new ErroneousConstantExpression();
                   break;
               }
               annotation.constant = constant;
 
@@ skipping 34 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements != null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }