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

sdk/lib/_internal/compiler/implementation/compiler.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;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 116 matching lines @@
 
   bool disableInlining = false;
 
   final Tracer tracer;
 
   CompilerTask measuredTask;
   Element _currentElement;
   LibraryElement coreLibrary;
   LibraryElement isolateLibrary;
   LibraryElement isolateHelperLibrary;
+  LibraryElement mirrorsLibrary;
   LibraryElement jsHelperLibrary;
   LibraryElement interceptorsLibrary;
   LibraryElement foreignLibrary;
   LibraryElement mainApp;
 
   ClassElement objectClass;
   ClassElement closureClass;
   ClassElement dynamicClass;
   ClassElement boolClass;
   ClassElement numClass;
@@ skipping 64 matching lines @@
   static const SourceString MAIN = const SourceString('main');
   static const SourceString CALL_OPERATOR_NAME = const SourceString('call');
   static const SourceString NO_SUCH_METHOD = const SourceString('noSuchMethod');
   static const int NO_SUCH_METHOD_ARG_COUNT = 1;
   static const SourceString CREATE_INVOCATION_MIRROR =
       const SourceString('createInvocationMirror');
   static const SourceString INVOKE_ON = const SourceString('invokeOn');
   static const SourceString RUNTIME_TYPE = const SourceString('runtimeType');
   static const SourceString START_ROOT_ISOLATE =
       const SourceString('startRootIsolate');
+  static const SourceString CREATE_MIRROR_SYSTEM =
+      const SourceString('_createMirrorSystem');
   bool enabledNoSuchMethod = false;
   bool enabledRuntimeType = false;
   bool enabledFunctionApply = false;
   bool enabledInvokeOn = false;
 
   Stopwatch progress;
 
   static const int PHASE_SCANNING = 0;
   static const int PHASE_RESOLVING = 1;
   static const int PHASE_COMPILING = 2;
@@ skipping 183 matching lines @@
     enqueuer.resolution.addToWorkList(
         isolateHelperLibrary.find(const SourceString('_currentIsolate')));
     enqueuer.resolution.addToWorkList(
         isolateHelperLibrary.find(const SourceString('_callInIsolate')));
     enqueuer.codegen.addToWorkList(
         isolateHelperLibrary.find(START_ROOT_ISOLATE));
   }
 
   bool hasIsolateSupport() => isolateLibrary != null;
 
+  void enableMirrorsSupport(LibraryElement element) {
+    mirrorsLibrary = element.patch;
+    enqueuer.resolution.addToWorkList(
+        mirrorsLibrary.find(CREATE_MIRROR_SYSTEM));
+    enqueuer.codegen.addToWorkList(
+        mirrorsLibrary.find(CREATE_MIRROR_SYSTEM));
+  }
+
+  bool hasMirrorsSupport() => mirrorsLibrary != null;
+
   /**
    * This method is called before [library] import and export scopes have been
    * set up.
    */
   void onLibraryScanned(LibraryElement library, Uri uri) {
     if (dynamicClass != null) {
       // When loading the built-in libraries, dynamicClass is null. We
       // take advantage of this as core imports js_helper and sees [dynamic]
       // this way.
       withCurrentElement(dynamicClass, () {
@@ skipping 553 matching lines @@
   // TODO(johnniwinther): Use [spannable] and [message] to provide better
   // information on assertion errors.
   if (condition is Function){
     condition = condition();
   }
   if (spannable == null || !condition) {
     throw new SpannableAssertionFailure(spannable, message);
   }
   return true;
 }