Mirrors implemented via patches. 2nd try.

sdk/lib/_internal/libraries.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.
 
 library libraries;
 
 /**
  * A bit flag used by [LibraryInfo] indicating that a library is used by dart2js
  */
 const int DART2JS_PLATFORM = 1;
@@ skipping 50 matching lines @@
 
   "json": const LibraryInfo(
       "json/json.dart"),
 
   "math": const LibraryInfo(
       "math/math.dart",
       dart2jsPatchPath: "_internal/compiler/implementation/lib/math_patch.dart"),
 
   "mirrors": const LibraryInfo(
       "mirrors/mirrors.dart",
-      dart2jsPath: "_internal/compiler/implementation/lib/mirrors.dart"),
+      dart2jsPatchPath: "_internal/compiler/implementation/lib/mirrors_patch.dart"),
 
   "nativewrappers": const LibraryInfo(
       "html/dartium/nativewrappers.dart",
       category: "Client",
       implementation: true,
       documented: false,
       platforms: VM_PLATFORM),
 
   "scalarlist": const LibraryInfo(
       "scalarlist/scalarlist.dart",
@@ skipping 89 matching lines @@
                     this.category: "Shared",
                     this.dart2jsPath,
                     this.dart2jsPatchPath,
                     this.implementation: false,
                     this.documented: true,
                     this.platforms: DART2JS_PLATFORM | VM_PLATFORM});
 
   bool get isDart2jsLibrary => (platforms & DART2JS_PLATFORM) != 0;
   bool get isVmLibrary => (platforms & VM_PLATFORM) != 0;
 }