Move InheritanceManager to its own file.

pkg/analyzer/test/generated/resolver_test.dart

 // Copyright (c) 2014, 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.generated.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/dart/resolver/inheritance_manager.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/java_engine_io.dart';
 import 'package:analyzer/src/generated/parser.dart' show ParserErrorCode;
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/generated/testing/ast_factory.dart';
 import 'package:analyzer/src/generated/testing/element_factory.dart';
 import 'package:analyzer/src/generated/testing/test_type_provider.dart';
@@ skipping 3620 matching lines @@
  */
 class _StaleElement extends ElementImpl {
   _StaleElement() : super("_StaleElement", -1);
 
   @override
   get kind => throw "_StaleElement's kind shouldn't be accessed";
 
   @override
   accept(_) => throw "_StaleElement shouldn't be visited";
 }