Better is/as check handling. With this CL, the subtype function in

test/codegen/language/type_literal_test.dart

Index: test/codegen/language/type_literal_test.dart
diff --git a/test/codegen/language/type_literal_test.dart b/test/codegen/language/type_literal_test.dart
index d0bba5d6f07c2fbf32254687cb494240af029b05..4260696f7c09baded2f5c43e2bac01887fc2848d 100644
--- a/test/codegen/language/type_literal_test.dart
+++ b/test/codegen/language/type_literal_test.dart
@@ -42,12 +42,12 @@ main() {
   testType(new Box<Box<Foo>>().typeArg, "Box<Foo>");
 
   // Typedef.
-  testType(Func, "Func");
-  testType(GenericFunc, "GenericFunc");
+  testType(Func, "Func((bool) -> int)");
+  testType(GenericFunc, "GenericFunc((bottom) -> int)");
 
   // TODO(rnystrom): This should print "GenericFunc<int>", but that isn't
   // implemented yet.
-  testType(new Box<GenericFunc<int>>().typeArg, "GenericFunc");
+  testType(new Box<GenericFunc<int>>().typeArg, "GenericFunc((int) -> int)");
 
   // Literals are canonicalized.
   Expect.identical(Foo, Foo);