Removed CLASS_ELEMENTS from BuildCompilationUnitElementTask and cleaned up comments

pkg/analyzer/test/src/task/dart_test.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 test.src.task.dart_test;
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 187 matching lines @@
 
   test_perform_library() {
     _performBuildTask(r'''
 library lib;
 import 'lib2.dart';
 export 'lib3.dart';
 part 'part.dart';
 class A {}
 class B = Object with A;
 ''');
-    expect(outputs, hasLength(3));
-    expect(outputs[CLASS_ELEMENTS], hasLength(2));
+    expect(outputs, hasLength(2));
     expect(outputs[COMPILATION_UNIT_ELEMENT], isNotNull);
     expect(outputs[RESOLVED_UNIT1], isNotNull);
   }
 
   void _performBuildTask(String content) {
     Source source = newSource('/test.dart', content);
     AnalysisTarget target = new LibrarySpecificUnit(source, source);
     _computeResult(target, RESOLVED_UNIT1);
     expect(task, new isInstanceOf<BuildCompilationUnitElementTask>());
   }
@@ skipping 1948 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result];
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }