Add UNITS and CLASS_ELEMENTS results.

pkg/analyzer/lib/task/dart.dart

 // Copyright (c) 2015, 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 analyzer.task.dart;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/scanner.dart';
@@ skipping 107 matching lines @@
 /**
  * The token stream produced while scanning a compilation unit.
  *
  * The value is the first token in the file, or the special end-of-file marker
  * at the end of the stream if the file does not contain any tokens.
  *
  * The result is only available for targets representing a Dart compilation unit.
  */
 final ResultDescriptor<Token> TOKEN_STREAM =
     new ResultDescriptor<Token>('TOKEN_STREAM', null);
+
+/**
+ * The sources of the Dart files that a library consists of.
+ *
+ * The list will include the source of the defining unit and [INCLUDED_PARTS].
+ * So, it is never empty or `null`.
+ *
+ * The result is only available for targets representing a Dart library.
+ */
+final ResultDescriptor<List<Source>> UNITS =
+    new ResultDescriptor<List<Source>>('UNITS', Source.EMPTY_ARRAY);