pkg/docgen: sort items in index.txt

pkg/docgen/lib/docgen.dart

 // Copyright (c) 2013, 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.
 
 /// **docgen** is a tool for creating machine readable representations of Dart
 /// code metadata, including: classes, members, comments and annotations.
 ///
 /// docgen is run on a `.dart` file or a directory containing `.dart` files.
 ///
 ///      $ dart docgen.dart [OPTIONS] [FILE/DIR]
@@ skipping 426 matching lines @@
 
     _writeToFile(JSON.encode(libraryMap), 'library_list.json');
 
     // Output libraries and classes to file after all information is generated.
     filteredEntities.where((e) => e is Class || e is Library).forEach((output) {
       _writeIndexableToFile(output, outputToYaml);
     });
 
     // Outputs all the qualified names documented with their type.
     // This will help generate search results.
-    _writeToFile(filteredEntities.map((e) =>
-        '${e.qualifiedName} ${e.typeName}').join('\n') + '\n',
+    var sortedEntities = filteredEntities.map((e) =>
+        '${e.qualifiedName} ${e.typeName}').toList()..sort();
+
+    _writeToFile(sortedEntities.join('\n') + '\n',
         'index.txt', append: append);
     var index = new Map.fromIterables(
         filteredEntities.map((e) => e.qualifiedName),
         filteredEntities.map((e) => e.typeName));
     if (append) {
       var previousIndex =
           JSON.decode(new File(
               '$_outputDirectory/index.json').readAsStringSync());
       index.addAll(previousIndex);
     }
@@ skipping 1802 matching lines @@
         .map((e) => originalMirror.getField(e.simpleName).reflectee)
         .where((e) => e != null)
         .toList();
   }
 
   Map toMap() => {
     'name': Indexable.getDocgenObject(mirror, owningLibrary).docName,
     'parameters': parameters
   };
 }