Implement subtype checks on type arguments.

sdk/lib/_internal/compiler/implementation/universe/universe.dart

 // Copyright (c) 2012, 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 universe;
 
 import '../closure.dart';
 import '../elements/elements.dart';
 import '../dart2jslib.dart';
 import '../tree/tree.dart';
@@ skipping 16 matching lines @@
    *
    * Invariant: Key elements are declaration elements.
    */
   Map<Element, CodeBuffer> generatedBailoutCode;
 
   /**
    * Documentation wanted -- johnniwinther
    *
    * Invariant: Elements are declaration elements.
    */
+  // TODO(karlklose): these sets should be merged.
   final Set<ClassElement> instantiatedClasses;
+  final Set<DartType> instantiatedTypes;
 
   /**
    * Documentation wanted -- johnniwinther
    *
    * Invariant: Elements are declaration elements.
    */
   final Set<FunctionElement> staticFunctionsNeedingGetter;
   final Map<SourceString, Set<Selector>> invokedNames;
   final Map<SourceString, Set<Selector>> invokedGetters;
   final Map<SourceString, Set<Selector>> invokedSetters;
   final Map<SourceString, Set<Selector>> fieldGetters;
   final Map<SourceString, Set<Selector>> fieldSetters;
   final Set<DartType> isChecks;
 
   Universe() : generatedCode = new Map<Element, CodeBuffer>(),
                generatedBailoutCode = new Map<Element, CodeBuffer>(),
                instantiatedClasses = new Set<ClassElement>(),
+               instantiatedTypes = new Set<DartType>(),
                staticFunctionsNeedingGetter = new Set<FunctionElement>(),
                invokedNames = new Map<SourceString, Set<Selector>>(),
                invokedGetters = new Map<SourceString, Set<Selector>>(),
                invokedSetters = new Map<SourceString, Set<Selector>>(),
                fieldGetters = new Map<SourceString, Set<Selector>>(),
                fieldSetters = new Map<SourceString, Set<Selector>>(),
                isChecks = new Set<DartType>();
 
   void addGeneratedCode(WorkItem work, CodeBuffer codeBuffer) {
     assert(invariant(work.element, work.element.isDeclaration));
@@ skipping 396 matching lines @@
     ClassElement cls = self;
     if (cls.isSubclassOf(other)) {
       // Resolve an invocation of [element.name] on [self]. If it
       // is found, this selector is a candidate.
       return hasElementIn(self, element) && appliesUntyped(element, compiler);
     }
 
     return false;
   }
 }