Implement is-checks against type variables.

sdk/lib/_internal/compiler/implementation/enqueue.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 EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
 
@@ skipping 68 matching lines @@
 
   /**
    * Adds [element] to the work list if it has not already been processed.
    *
    * Returns [:true:] if the [element] should be processed.
    */
   // TODO(johnniwinther): Change to 'Returns true if the element was added to
   // the work list'?
   bool addElementToWorkList(Element element, [TreeElements elements]);
 
+  void registerInstantiatedType(InterfaceType type) {
+    universe.instantiatedTypes.add(type);
+    registerInstantiatedClass(type.element);
+  }
+
   void registerInstantiatedClass(ClassElement cls) {
     if (universe.instantiatedClasses.contains(cls)) return;
     if (!cls.isAbstract(compiler)) {
       universe.instantiatedClasses.add(cls);
       onRegisterInstantiatedClass(cls);
+    } else {
+      // For factories and instantiations of [List], the target is abstract.
+      // Since we may need the type arguments for constructing the instance,
+      // we register the class to be added to the classes needing rti.
+      compiler.world.registerInstantiatedAbstractClass(cls);

[ngeoffray, 2013/02/26 14:11:37]

Instead of doing this here, it looks a bit cleaner to add factory constructors.
So the check could be whenever you enqueue a factory constructor of an abstract
class.

[karlklose, 2013/02/27 10:12:58]

I moved the code to addToWorklist.

+      compiler.backend.registerRuntimeType();

[ngeoffray, 2013/02/26 14:11:37]

You should not register this here.

[karlklose, 2013/02/27 10:12:58]

Removed. Fixed a bug with registering getRuntimeTypeArgument correclty in the
resolver now.

     }
     compiler.backend.registerInstantiatedClass(cls, this);
   }
 
   bool checkNoEnqueuedInvokedInstanceMethods() {
     task.measure(() {
       // Run through the classes and see if we need to compile methods.
       for (ClassElement classElement in universe.instantiatedClasses) {
         for (ClassElement currentClass = classElement;
              currentClass != null;
@@ skipping 425 matching lines @@
     while(!queue.isEmpty) {
       // TODO(johnniwinther): Find an optimal process order for codegen.
       f(queue.removeLast());
     }
   }
 
   void _logSpecificSummary(log(message)) {
     log('Compiled ${generatedCode.length} methods.');
   }
 }