Concept of how dart:mirrors LibraryMirror, ClassMirror can be implemented in dart2js.

sdk/lib/_internal/compiler/implementation/enqueue.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.
 
 part of dart2js;
 
 class EnqueueTask extends CompilerTask {
   final Enqueuer codegen;
   final Enqueuer resolution;
 
@@ skipping 99 matching lines @@
       compiler.enabledInvokeOn = true;
     }
 
     // Enable isolate support if we start using something from the
     // isolate library.
     LibraryElement library = element.getLibrary();
     if (!compiler.hasIsolateSupport()
         && library.uri.toString() == 'dart:isolate') {
       compiler.enableIsolateSupport(library);
     }
+    else if (!compiler.hasMirrorsSupport()
+        && library.uri.toString() == 'dart:mirrors') {
+      compiler.enableMirrorsSupport(library);
+    }
 
     nativeEnqueuer.registerElement(element);
   }
 
   /**
    * Documentation wanted -- johnniwinther
    *
    * Invariant: [element] must be a declaration element.
    */
   void eagerRecompile(Element element) {
@@ skipping 287 matching lines @@
 
   String toString() => 'Enqueuer($name)';
 
   void logSummary(log(message)) {
     log(isResolutionQueue
         ? 'Resolved ${resolvedElements.length} elements.'
         : 'Compiled ${universe.generatedCode.length} methods.');
     nativeEnqueuer.logSummary(log);
   }
 }