Add Class.isEnum to Kernel and use it to resynthesize enums in Analyzer.

pkg/analyzer/test/src/summary/resynthesize_kernel_test.dart

 // Copyright (c) 2017, 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 analyzer.test.src.summary.resynthesize_kernel_test;
 
 import 'dart:async';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 280 matching lines @@
   test_const_topLevel_super() async {
     await super.test_const_topLevel_super();
   }
 
   @failingTest
   test_const_topLevel_this() async {
     await super.test_const_topLevel_this();
   }
 
   @failingTest
-  test_constExpr_pushReference_enum_field() async {
-    await super.test_constExpr_pushReference_enum_field();
-  }
-
-  @failingTest
-  test_constExpr_pushReference_enum_method() async {
-    await super.test_constExpr_pushReference_enum_method();
-  }
-
-  @failingTest
   test_constructor_initializers_assertInvocation() async {
     await super.test_constructor_initializers_assertInvocation();
   }
 
   @failingTest
   test_constructor_initializers_assertInvocation_message() async {
     await super.test_constructor_initializers_assertInvocation_message();
   }
 
   @failingTest
@@ skipping 86 matching lines @@
   test_enum_documented() async {
     await super.test_enum_documented();
   }
 
   @failingTest
   test_enum_value_documented() async {
     await super.test_enum_value_documented();
   }
 
   @failingTest
-  test_enum_values() async {
-    await super.test_enum_values();
-  }
-
-  @failingTest
-  test_enums() async {
-    await super.test_enums();
-  }
-
-  @failingTest
   test_error_extendsEnum() async {
     await super.test_error_extendsEnum();
   }
 
   @failingTest
   test_executable_parameter_type_typedef() async {
     await super.test_executable_parameter_type_typedef();
   }
 
   @failingTest
@@ skipping 502 matching lines @@
   test_type_reference_part_to_other_part() async {
     await super.test_type_reference_part_to_other_part();
   }
 
   @failingTest
   test_type_reference_part_to_part() async {
     await super.test_type_reference_part_to_part();
   }
 
   @failingTest
-  test_type_reference_to_enum() async {
-    await super.test_type_reference_to_enum();
-  }
-
-  @failingTest
   test_type_reference_to_import() async {
     await super.test_type_reference_to_import();
   }
 
   @failingTest
   test_type_reference_to_import_export() async {
     await super.test_type_reference_to_import_export();
   }
 
   @failingTest
@@ skipping 315 matching lines @@
   @override
   Future<List<int>> readAsBytes() async {
     return file.readAsBytesSync();
   }
 
   @override
   Future<String> readAsString() async {
     return file.readAsStringSync();
   }
 }