pkg/csslib: remove unused vars and fields

test/mixin_test.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.
 
 library mixin_test;
 
 import 'package:unittest/unittest.dart';
 import 'testing.dart';
 
 final options = ['--warnings_as_errors', '--no-colors', 'memory'];
@@ skipping 440 matching lines @@
 @mixin a {
   span {
     border: 2px dashed red;
   }
   @include b;
 }
 
 @include a;
   ''';
 
-  var generated = r'''span {
-  border: 2px dashed #f00;
-}''';
-
   var stylesheet = compileCss(input, errors: errors, opts: options);
   expect(stylesheet != null, true);
   expect(errors.length, 1, reason: errors.toString());
   var error = errors[0];
   expect(error.message, 'Using declaration mixin b as top-level mixin');
   expect(error.span.start.line, 8);
   expect(error.span.end.offset, 90);
 }
 
 void emptyMixin() {
@@ skipping 180 matching lines @@
     test('multiple args and var decls as args', mixinManyArgs);
   });
 
   group('Mixin warnings', () {
     test('undefined top-level', undefinedTopLevel);
     test('undefined declaration', undefinedDeclaration);
     test('detect bad top-level as declaration', badDeclarationInclude);
     test('detect bad declaration as top-level', badTopInclude);
   });
 }