Implement is-checks against type variables.

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

Index: sdk/lib/_internal/compiler/implementation/enqueue.dart
diff --git a/sdk/lib/_internal/compiler/implementation/enqueue.dart b/sdk/lib/_internal/compiler/implementation/enqueue.dart
index 1036a57eb779e6d256f3c1da586785959dd3f464..17ded6ca4bdb05ac869930f7365eee323ccfde71 100644
--- a/sdk/lib/_internal/compiler/implementation/enqueue.dart
+++ b/sdk/lib/_internal/compiler/implementation/enqueue.dart
@@ -86,11 +86,22 @@ abstract class Enqueuer {
   // 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);
   }