Make TypedefMirror a direct descendant of TypeMirror.

runtime/lib/mirrors_patch.dart

Index: runtime/lib/mirrors_patch.dart
diff --git a/runtime/lib/mirrors_patch.dart b/runtime/lib/mirrors_patch.dart
index 5b7539b637258d038227a96db76732d8dd2f2a86..c1090abe5ffa54fce659ec361e0a5efe4802b01b 100644
--- a/runtime/lib/mirrors_patch.dart
+++ b/runtime/lib/mirrors_patch.dart
@@ -41,6 +41,10 @@ patch ClassMirror reflectClass(Type key) {
   return _Mirrors.reflectClass(key);
 }
 
+patch TypeMirror reflectType(Type key) {
+  return _Mirrors.reflectType(key);
+}
+
 patch class MirrorSystem {
   /* patch */ static String getName(Symbol symbol) {
     return _symbol_dev.Symbol.getName(symbol);