Make TypedefMirror a direct descendant of TypeMirror.

sdk/lib/_internal/lib/js_mirrors.dart

Index: sdk/lib/_internal/lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/lib/js_mirrors.dart b/sdk/lib/_internal/lib/js_mirrors.dart
index deb2faa2297f2d0e56eac9f45a8ebc4fa2d66dd6..1c94ecdcacf5b794ef027cf10381cc130e8c3b54 100644
--- a/sdk/lib/_internal/lib/js_mirrors.dart
+++ b/sdk/lib/_internal/lib/js_mirrors.dart
@@ -408,14 +408,14 @@ InstanceMirror reflect(Object reflectee) {
   }
 }
 
-ClassMirror reflectType(Type key) {
+TypeMirror reflectType(Type key) {
   // TODO(ahe): Don't discard type arguments to support
   // [ClassMirror.isOriginalDeclaration] and [ClassMirror.originalDeclaration]
   // correctly.
   return reflectClassByMangledName(getMangledTypeName(key).split('<')[0]);
 }
 
-ClassMirror reflectClassByMangledName(String mangledName) {
+TypeMirror reflectClassByMangledName(String mangledName) {
   String unmangledName = mangledGlobalNames[mangledName];
   if (unmangledName == null) unmangledName = mangledName;
   return reflectClassByName(s(unmangledName), mangledName);
@@ -423,7 +423,7 @@ ClassMirror reflectClassByMangledName(String mangledName) {
 
 var classMirrors;
 
-ClassMirror reflectClassByName(Symbol symbol, String mangledName) {
+TypeMirror reflectClassByName(Symbol symbol, String mangledName) {
   if (classMirrors == null) classMirrors = JsCache.allocate();
   var mirror = JsCache.fetch(classMirrors, mangledName);
   if (mirror != null) return mirror;