Add ElementKind for factory constructors.

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
@@ skipping 69 matching lines @@
         return const ResolutionImpact();
       }
 
       WorldImpact processMetadata([WorldImpact result]) {
         for (MetadataAnnotation metadata in element.implementation.metadata) {
           metadata.ensureResolved(resolution);
         }
         return result;
       }
 
-      ElementKind kind = element.kind;
-      if (identical(kind, ElementKind.GENERATIVE_CONSTRUCTOR) ||
-          identical(kind, ElementKind.FUNCTION) ||
-          identical(kind, ElementKind.GETTER) ||
-          identical(kind, ElementKind.SETTER)) {
+      if (element.isConstructor ||
+          element.isFunction ||
+          element.isGetter ||
+          element.isSetter) {
         return processMetadata(resolveMethodElement(element));
       }
 
-      if (identical(kind, ElementKind.FIELD)) {
+      if (element.isField) {
         return processMetadata(resolveField(element));
       }
       if (element.isClass) {
         ClassElement cls = element;
         cls.ensureResolved(resolution);
         return processMetadata(const ResolutionImpact());
       } else if (element.isTypedef) {
         TypedefElement typdef = element;
         return processMetadata(resolveTypedef(typdef));
       }
@@ skipping 966 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements !=null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }