Optimize subclass/subtype queries

pkg/compiler/lib/src/js_backend/codegen/glue.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 code_generator_dependencies;
 
 import '../backend_helpers.dart' show
     BackendHelpers;
 import '../js_backend.dart';
 
@@ skipping 210 matching lines @@
   }
 
   int getTypeVariableIndex(TypeVariableType variable) {
     return variable.element.index;
   }
 
   bool needsSubstitutionForTypeVariableAccess(ClassElement cls) {
     ClassWorld classWorld = _compiler.world;
     if (classWorld.isUsedAsMixin(cls)) return true;
 
-    Iterable<ClassElement> subclasses = _compiler.world.strictSubclassesOf(cls);
-    return subclasses.any((ClassElement subclass) {
+    return _compiler.world.anyStrictSubclassOf(cls, (ClassElement subclass) {
       return !_backend.rti.isTrivialSubstitution(subclass, cls);
     });
   }
 
   js.Expression generateTypeRepresentation(DartType dartType,
                                            List<js.Expression> arguments,
                                            CodegenRegistry registry) {
     int variableIndex = 0;
     js.Expression representation = _backend.rtiEncoder.getTypeRepresentation(
         dartType,
@@ skipping 51 matching lines @@
   FunctionElement get closureFromTearOff => _backend.helpers.closureFromTearOff;
 
   js.Name registerOneShotInterceptor(Selector selector) {
     return _backend.registerOneShotInterceptor(selector);
   }
 
   bool mayGenerateInstanceofCheck(DartType type) {
     return _backend.mayGenerateInstanceofCheck(type);
   }
 }