Implement is-checks against type variables.

sdk/lib/_internal/compiler/implementation/world.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.
 
 part of dart2js;
 
 class World {
   final Compiler compiler;
   final Map<ClassElement, Set<ClassElement>> subtypes;
   final Map<ClassElement, Set<MixinApplicationElement>> mixinUses;
   final Map<ClassElement, Set<ClassElement>> typesImplementedBySubclasses;
   final Set<ClassElement> classesNeedingRti;
   final Map<ClassElement, Set<ClassElement>> rtiDependencies;
   final FunctionSet userDefinedGetters;
   final FunctionSet userDefinedSetters;
+  Link<ClassElement> classesUsingTypeVariableTests;
 
   World(Compiler compiler)
       : subtypes = new Map<ClassElement, Set<ClassElement>>(),
         mixinUses = new Map<ClassElement, Set<MixinApplicationElement>>(),
         typesImplementedBySubclasses =
             new Map<ClassElement, Set<ClassElement>>(),
         userDefinedGetters = new FunctionSet(compiler),
         userDefinedSetters = new FunctionSet(compiler),
         classesNeedingRti = new Set<ClassElement>(),
         rtiDependencies = new Map<ClassElement, Set<ClassElement>>(),
+        classesUsingTypeVariableTests = const Link<ClassElement>(),
         this.compiler = compiler;
 
   void populate() {
     void addSubtypes(ClassElement cls) {
       if (cls.resolutionState != STATE_DONE) {
         compiler.internalErrorOnElement(
             cls, 'Class "${cls.name.slowToString()}" is not resolved.');
       }
 
       for (DartType type in cls.allSupertypes) {
@@ skipping 176 matching lines @@
     MemberSet memberSet = _memberSetFor(type, noSuchMethodSelector);
     for (Element element in memberSet.elements) {
       ClassElement holder = element.getEnclosingClass();
       if (!identical(holder, compiler.objectClass) &&
           noSuchMethodSelector.applies(element, compiler)) {
         result.add(holder);
       }
     }
     return result;
   }
+
+  /**
+   * Register a class that contains an is-test against one of it type variables.
+   * The class and all its subtypes need runtime type information and we need to
+   * register the type arguments of their instantiations.
+   */
+  registerTypeVariableCheck(ClassElement cls) {
+    classesUsingTypeVariableTests = classesUsingTypeVariableTests.prepend(cls);
+    classesNeedingRti.add(cls);
+  }
 }
 
 /**
  * A [MemberSet] contains all the possible targets for a selector.
  */
 class MemberSet {
   final Set<Element> elements;
   final SourceString name;
 
   MemberSet(SourceString this.name) : elements = new Set<Element>();
 
   void add(Element element) {
     elements.add(element);
   }
 
   bool get isEmpty => elements.isEmpty;
 }