Implement is-checks against type variables.

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

Index: sdk/lib/_internal/compiler/implementation/world.dart
diff --git a/sdk/lib/_internal/compiler/implementation/world.dart b/sdk/lib/_internal/compiler/implementation/world.dart
index 271629bf64132666df45a3b3aba08074886ca86e..ba18905df735b4f76518da06424ee257793df1b9 100644
--- a/sdk/lib/_internal/compiler/implementation/world.dart
+++ b/sdk/lib/_internal/compiler/implementation/world.dart
@@ -53,6 +53,8 @@ class World {
 
     compiler.resolverWorld.instantiatedClasses.forEach(addSubtypes);
 
+    compiler.backend.addBackendRtiDependencies(this);

[ngeoffray, 2013/02/27 16:18:37]

Explain why you're doing this, and why now.

[karlklose, 2013/02/28 11:37:46]

Done.

+
     // Find the classes that need runtime type information. Such
     // classes are:
     // (1) used in a is check with type variables,
@@ -79,12 +81,23 @@ class World {
       }
     }
 
+    Set<ClassElement> classesUsingTypeVariableTests = new Set<ClassElement>();
     compiler.resolverWorld.isChecks.forEach((DartType type) {
-      if (type is InterfaceType) {
+      if (type.kind == TypeKind.TYPE_VARIABLE) {
+        TypeVariableElement variable = type.element;
+        classesUsingTypeVariableTests.add(variable.enclosingElement);
+      }
+    });
+    compiler.resolverWorld.addImplicitChecks(classesUsingTypeVariableTests);
+    compiler.resolverWorld.isChecks.forEach((DartType type) {
+      if (type.kind == TypeKind.INTERFACE) {
         InterfaceType itf = type;
         if (!itf.isRaw) {
           potentiallyAddForRti(itf.element);
         }
+      } else if (type.kind == TypeKind.TYPE_VARIABLE) {
+        TypeVariableElement variable = type.element;
+        potentiallyAddForRti(variable.enclosingElement);
       }
     });
   }
@@ -102,7 +115,6 @@ class World {
     return uses != null && !uses.isEmpty;
   }
 
-
   void registerRtiDependency(Element element, Element dependency) {
     // We're not dealing with typedef for now.
     if (!element.isClass() || !dependency.isClass()) return;