Add ElementKind for factory constructors.

tests/compiler/dart2js/semantic_visitor_test_decl_data.dart

 // Copyright (c) 2015, 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.
 
 part of dart2js.semantics_visitor_test;
 
 const Map<String, List<Test>> DECL_TESTS = const {
   'Function declarations': const [
     const Test(
         '''
@@ skipping 518 matching lines @@
         ],
         method: ''),
     const Test.clazz(
         '''
         class C {
           factory C(a, b) => null;
         }
         ''',
         const [
           const Visit(VisitKind.VISIT_FACTORY_CONSTRUCTOR_DECL,
-              element: 'function(C#)',
+              element: 'factory_constructor(C#)',
               parameters: '(a,b)',
               body: '=>null;'),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#a)',
               index: 0),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#b)',
               index: 1),
         ],
         method: ''),
     const Test.clazz(
         '''
         class C {
           factory C(a, b) = C._;
           C._(a, b);
         }
         ''',
         const [
           const Visit(VisitKind.VISIT_REDIRECTING_FACTORY_CONSTRUCTOR_DECL,
-              element: 'function(C#)',
+              element: 'factory_constructor(C#)',
               parameters: '(a,b)',
               target: 'generative_constructor(C#_)',
               type: 'C'),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#a)',
               index: 0),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#b)',
               index: 1),
         ],
         method: ''),
     const Test.clazz(
         '''
         class C {
           factory C(a, b) = D;
         }
         class D<T> {
           D(a, b);
         }
         ''',
         const [
           const Visit(VisitKind.VISIT_REDIRECTING_FACTORY_CONSTRUCTOR_DECL,
-              element: 'function(C#)',
+              element: 'factory_constructor(C#)',
               parameters: '(a,b)',
               target: 'generative_constructor(D#)',
               type: 'D'),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#a)',
               index: 0),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#b)',
               index: 1),
         ],
         method: ''),
     const Test.clazz(
         '''
         class C {
           factory C(a, b) = D<int>;
         }
         class D<T> {
           D(a, b);
         }
         ''',
         const [
           const Visit(VisitKind.VISIT_REDIRECTING_FACTORY_CONSTRUCTOR_DECL,
-              element: 'function(C#)',
+              element: 'factory_constructor(C#)',
               parameters: '(a,b)',
               target: 'generative_constructor(D#)',
               type: 'D<int>'),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#a)',
               index: 0),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#b)',
               index: 1),
         ],
         method: ''),
     const Test.clazz(
         '''
         class C {
           factory C(a, b) = D<int>;
         }
         class D<T> {
           factory D(a, b) = E<D<T>>;
         }
         class E<S> {
           E(a, b);
         }
         ''',
         const [
           const Visit(VisitKind.VISIT_REDIRECTING_FACTORY_CONSTRUCTOR_DECL,
-              element: 'function(C#)',
+              element: 'factory_constructor(C#)',
               parameters: '(a,b)',
-              target: 'function(D#)',
+              target: 'factory_constructor(D#)',
               type: 'D<int>'),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#a)',
               index: 0),
           const Visit(VisitKind.VISIT_REQUIRED_PARAMETER_DECL,
               element: 'parameter(#b)',
               index: 1),
         ],
         method: ''),
   ],
@@ skipping 217 matching lines @@
         '''
         const m = 42;
         ''',
         const [
           const Visit(VisitKind.VISIT_TOP_LEVEL_CONSTANT_DECL,
                 element: 'field(m)',
                 constant: 42),
         ]),
   ],
 };