First half of the new HTML json docs.

tools/html_json_doc/lib/html_to_json.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 for extracting the documentation comments from files generated by
  * the HTML library. The comments are stored in a JSON file.
  *
  * Comments must be in either the block style with leading *s:
  *
  *     /**
  *      * Comment here.
  *      */
  *
  * Or the triple-slash style:
  *
  *     /// Docs go here.
  *     /// And here.
  *
  * Each member that is to be documented should be preceeded by a meta-comment
  * containing the string `@docsEditable` such as:
  *
  *     /// @docsEditable
  */
 library html_to_json;
 
 import 'dart:json';
 import 'dart:io';
+import 'dart:async';
 
 
 /// True if any errors were triggered through the conversion.
 bool _anyErrors = false;
 
 
 /**
  * Convert files on [htmlPath] and write JSON to [jsonPath].
  */
 Future<bool> convert(Path htmlPath, Path jsonPath) {
@@ skipping 269 matching lines @@
         '${prettyPrintJson(json[key], '$indentation  ')}');
     var recursiveOutput = Strings.join(mapList, ',\n');
     output = '$indentation{\n'
       '$recursiveOutput'
       '\n$indentation}';
   } else {
     output = '$indentation${JSON.stringify(json)}';
   }
   return output;
 }