Fix 'collection' tests and co19 dartc/dart2js status files.

tests/html/element_classes_test.dart

 // Copyright (c) 2011, 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 ElementTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:collection';
 import 'dart:html';
 
@@ skipping 132 matching lines @@
   });
 
   test('toggleAll', () {
     final classes = makeClassSet();
     classes.toggleAll(['bar', 'foo']);
     expect(classes, orderedEquals(['baz']));
     classes.toggleAll(['qux', 'quux']);
     expect(classes, orderedEquals(['baz', 'qux', 'quux']));
   });
 
-  test('isSubsetOf', () {
-    final classes = makeClassSet();
-    expect(classes.isSubsetOf(['foo', 'bar', 'baz'].toSet()), isTrue);
-    expect(classes.isSubsetOf(['foo', 'bar', 'baz', 'qux'].toSet()), isTrue);
-    expect(classes.isSubsetOf(['foo', 'bar', 'qux'].toSet()), isFalse);
-  });
-
   test('containsAll', () {
     final classes = makeClassSet();
     expect(classes.containsAll(['foo', 'baz'].toSet()), isTrue);
     expect(classes.containsAll(['foo', 'qux'].toSet()), isFalse);
   });
 
   test('intersection', () {
     final classes = makeClassSet();
     expect(classes.intersection(['foo', 'qux', 'baz'].toSet()),
         unorderedEquals(['foo', 'baz']));
   });
 
   test('clear', () {
     final classes = makeClassSet();
     classes.clear();
     expect(classes, equals([]));
   });
 
   test('order', () {
     var classes = makeClassSet();
     classes.add('aardvark');
     expect(classes, orderedEquals(['foo', 'bar', 'baz', 'aardvark']));
     classes.toggle('baz');
     expect(classes, orderedEquals(['foo', 'bar', 'aardvark']));
     classes.toggle('baz');
     expect(classes, orderedEquals(['foo', 'bar', 'aardvark', 'baz']));
   });
 }