Revert "Converting dart:html to use DateTime rather than Date."

tests/html/fileapi_test.dart

 library fileapi;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 void fail(message) {
   guardAsync(() {
     expect(false, isTrue, reason: message);
   });
 }
@@ skipping 74 matching lines @@
             }));
       });
 
       test('fileCreate', () {
         fs.root.getFile(
             'file4',
             options: {'create': true},
             successCallback: expectAsync1((FileEntry e) {
               expect(e.name, equals('file4'));
               expect(e.isFile, isTrue);
-
-              e.getMetadata(expectAsync1((Metadata metadata) {
-                var changeTime = metadata.modificationTime;
-                expect(new DateTime.now().difference(changeTime).inSeconds,
-                  lessThan(60));
-              }));
             }),
             errorCallback: (e) {
               fail('Got file error: ${e.code}');
             });
         });
     }
   });
 }