Revert "Optimize subclass/subtype queries"

pkg/compiler/lib/src/js_emitter/js_emitter.dart

 // Copyright (c) 2013, 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.js_emitter;
 
 import 'package:js_ast/src/precedence.dart' as js_precedence;
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
 import 'package:js_runtime/shared/embedded_names.dart' show JsBuiltin;
 
 
 import '../common.dart';
 import '../common/names.dart' show
     Identifiers;
 import '../common/tasks.dart' show
     CompilerTask;
 import '../compiler.dart' show
     Compiler;
 import '../constants/values.dart';
 import '../closure.dart' show
     ClosureClassElement,
     ClosureClassMap,
     ClosureFieldElement,
     CapturedVariable;
-import '../core_types.dart' show
-    CoreClasses;
 import '../dart_types.dart' show
     DartType,
     FunctionType,
     InterfaceType,
     TypedefType,
     Types,
     TypeVariableType;
 import '../deferred_load.dart' show
     OutputUnit;
 import '../elements/elements.dart' show
@@ skipping 53 matching lines @@
 part 'code_emitter_task.dart';
 part 'helpers.dart';
 part 'interceptor_stub_generator.dart';
 part 'main_call_stub_generator.dart';
 part 'metadata_collector.dart';
 part 'native_emitter.dart';
 part 'native_generator.dart';
 part 'parameter_stub_generator.dart';
 part 'runtime_type_generator.dart';
 part 'type_test_registry.dart';