Refactoring two pieces of polymer:

pkg/polymer/lib/src/build/mirrors_remover.dart

+// Copyright (c) 2014, 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.
+
+/// Transformer that removes uses of mirrors from the polymer runtime, so that
+/// deployed applications are thin and small.
+library polymer.src.build.mirrors_remover;
+
+import 'dart:async';
+import 'package:barback/barback.dart';
+
+/// Removes the code-initialization logic based on mirrors.
+class MirrorsRemover extends Transformer {
+  MirrorsRemover.asPlugin();
+
+  /// Only apply to `lib/polymer.dart`.
+  Future<bool> isPrimary(Asset input) => new Future.value(
+      input.id.package == 'polymer' &&
+      input.id.path == 'lib/polymer.dart');
+
+  Future apply(Transform transform) {
+    var id = transform.primaryInput.id;
+    return transform.primaryInput.readAsString().then((code) {
+      // Note: this rewrite is highly-coupled with how polymer.dart is
+      // written. Make sure both are updated in sync.
+      var start = code.indexOf('@MirrorsUsed');
+      if (start == -1) _error();
+      var end = code.indexOf('show MirrorsUsed;', start);
+      if (end == -1) _error();
+      var sb = new StringBuffer()
+          ..write(code.substring(0, start))
+          ..write(code.susbtring(end)
+              .replaceAll('mirror_loader', 'static_loader')):
+
+      transform.addOutput(new Asset.fromString(id, sb.toString()));
+    });
+  }
+}
+
+/** Transformer phases which should be applied to the smoke package. */
+List<List<Transformer>> get phasesForSmoke =>
+    [[new MirrorsRemover.asPlugin()]];
+
+_error() => throw new StateError("Couldn't remove imports to mirrors, maybe "
+    "polymer.dart was modified, but mirrors_remover.dart wasn't.");