Add a mode to dartdoc to generate the navigation on the client.

utils/dartdoc/classify.dart

Index: utils/dartdoc/classify.dart
diff --git a/utils/dartdoc/classify.dart b/utils/dartdoc/classify.dart
index aad85f5c87ea106f7490b7e9f50794e7de945e1f..1057b0a37a6d589fe43c0fcd387a67ee7f17358f 100644
--- a/utils/dartdoc/classify.dart
+++ b/utils/dartdoc/classify.dart
@@ -2,6 +2,11 @@
 // 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('classify');
+
+#import('../../frog/lang.dart');
+#import('markdown.dart', prefix: 'md');
+
 /**
  * Kinds of tokens that we care to highlight differently. The values of the
  * fields here will be used as CSS class names for the generated spans.