Revert "dart2js_mirrors_test added"

lib/mirrors/mirrors.dart

Index: lib/mirrors/mirrors.dart
diff --git a/lib/mirrors/mirrors.dart b/lib/mirrors/mirrors.dart
index 01f915b5567193d1fc0dd2a44cfa1ebbc892f658..88d9a7db28cca8ce2908db5bc7556a12a94cbee6 100644
--- a/lib/mirrors/mirrors.dart
+++ b/lib/mirrors/mirrors.dart
@@ -55,7 +55,6 @@ abstract class MirrorSystem {
 /**
  * Returns a [MirrorSystem] for the current isolate.
  */
-// TODO(johnniwinther): Implement this as an external function.
 MirrorSystem currentMirrorSystem() {
   return _Mirrors.currentMirrorSystem();
 }
@@ -64,7 +63,6 @@ MirrorSystem currentMirrorSystem() {
  * Creates a [MirrorSystem] for the isolate which is listening on
  * the [SendPort].
  */
-// TODO(johnniwinther): Implement this as an external function.
 Future<MirrorSystem> mirrorSystemOf(SendPort port) {
   return _Mirrors.mirrorSystemOf(port);
 }
@@ -75,7 +73,6 @@ Future<MirrorSystem> mirrorSystemOf(SendPort port) {
  * This only works if this mirror system is associated with the
  * current running isolate.
  */
-// TODO(johnniwinther): Implement this as an external function.
 InstanceMirror reflect(Object reflectee) {
   return _Mirrors.reflect(reflectee);
 }