Support runtime check of function types.

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

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index 0af15cc21f932a7588bd144044a93689263d01e3..d48a126c2d23167a90f4b0bb3674fc702cd45f1e 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -155,6 +155,11 @@ abstract class Backend {
   void registerFallThroughError(TreeElements elements) {}
   void registerSuperNoSuchMethod(TreeElements elements) {}
   void registerConstantMap(TreeElements elements) {}
+  /**
+   * Called this to register that a getter exists for a function on an
+   * instantiated generic class.
+   */
+  void registerGenericClosure(Enqueuer enqueuer, TreeElements elements) {}
   void registerRuntimeType(TreeElements elements) {}
 
   bool isNullImplementation(ClassElement cls) {