Revert "Merge more Kernel infrastructure from kernel_sdk SDK fork."

runtime/lib/mirrors_patch.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import "dart:async" show Future;
-import "dart:collection" show UnmodifiableListView, UnmodifiableMapView;
 import "dart:_internal" as internal;
 
 /**
  * Returns a [MirrorSystem] for the current isolate.
  */
 @patch MirrorSystem currentMirrorSystem() {
   return _Mirrors.currentMirrorSystem();
 }
 
 /**
@@ skipping 44 matching lines @@
         ((name.length > 0) && (name[0] == '_') && (library == null))) {
       throw new ArgumentError(library);
     }
     if (library != null) name = _mangleName(name, library._reflectee);
     return new internal.Symbol.unvalidated(name);
   }
 
   static _mangleName(String name, _MirrorReference lib)
       native "Mirrors_mangleName";
 }