Make TypedefMirror a direct descendant of TypeMirror.

tests/lib/mirrors/function_type_mirror_test.dart

Index: tests/lib/mirrors/function_type_mirror_test.dart
diff --git a/tests/lib/mirrors/function_type_mirror_test.dart b/tests/lib/mirrors/function_type_mirror_test.dart
index 4376c83cf44240e139475be5c6c5cd4dcf31a7d1..132485a00801947330973ddc61d95bc3f491426a 100644
--- a/tests/lib/mirrors/function_type_mirror_test.dart
+++ b/tests/lib/mirrors/function_type_mirror_test.dart
@@ -11,7 +11,7 @@ typedef void FooFunction(int a, double b);
 bar(int a) {}
 
 main() {
-  TypedefMirror tm = reflectClass(FooFunction);
+  TypedefMirror tm = reflectType(FooFunction);
   FunctionTypeMirror ftm = tm.referent;
   Expect.equals(const Symbol("void"), ftm.returnType.simpleName);
   Expect.equals(const Symbol("int"), ftm.parameters[0].type.simpleName);