Start a whitelist of methods those optionals should be treated as named formals in dart:html.

tests/html/fileapi_test.dart

 #library('fileapi');
 #import('../../pkg/unittest/unittest.dart');
 #import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 
 void fail(message) {
   guardAsync(() {
     Expect.fail(message);
   });
 }
 
 DOMFileSystem fs;
 
 main() {
   useHtmlConfiguration();
   test('getFileSystem', () {
     window.webkitRequestFileSystem(LocalWindow.TEMPORARY, 100, expectAsync1(
       (DOMFileSystem fileSystem) {
         fs = fileSystem;
       }),
       (e) {
         fail('Got file error: ${e.code}');
       });
   });
   group('getDirectory', () {
 
     test('directoryDoesntExist', () {
-      /* OPTIONALS
       fs.root.getDirectory(
           'directory2',
           options: {},
           successCallback: (e) {
             fail('Should not be reached');
           },
           errorCallback: expectAsync1((FileError e) {
             expect(e.code, equals(FileError.NOT_FOUND_ERR));
           }));
-      */
-      fs.root.getDirectory(
-          'directory2',
-          {},
-          (e) {
-            fail('Should not be reached');
-          },
-          expectAsync1((FileError e) {
-            expect(e.code, equals(FileError.NOT_FOUND_ERR));
-          }));
     });
 
     test('directoryCreate', () {
-      /* OPTIONALS
       fs.root.getDirectory(
           'directory3',
           options: {'create': true},
           successCallback: expectAsync1((DirectoryEntry e) {
             expect(e.name, equals('directory3'));
           }),
           errorCallback: (e) {
             fail('Got file error: ${e.code}');
           });
-      */
-      fs.root.getDirectory(
-          'directory3',
-          {'create': true},
-          expectAsync1((DirectoryEntry e) {
-            expect(e.name, equals('directory3'));
-          }),
-          (e) {
-            fail('Got file error: ${e.code}');
-          });
     });
   });
 
   group('getFile', () {
 
     test('fileDoesntExist', () {
-      /* OPTIONALS
       fs.root.getFile(
           'file2',
           options: {},
           successCallback: (e) {
             fail('Should not be reached');
           },
           errorCallback: expectAsync1((FileError e) {
             expect(e.code, equals(FileError.NOT_FOUND_ERR));
           }));
-      */
-      fs.root.getFile(
-          'file2',
-          {},
-          (e) {
-            fail('Should not be reached');
-          },
-          expectAsync1((FileError e) {
-            expect(e.code, equals(FileError.NOT_FOUND_ERR));
-          }));
     });
 
     test('fileCreate', () {
-      /* OPTIONALS
       fs.root.getFile(
           'file4',
           options: {'create': true},
           successCallback: expectAsync1((FileEntry e) {
             expect(e.name, equals('file4'));
             expect(e.isFile, equals(true));
           }),
           errorCallback: (e) {
             fail('Got file error: ${e.code}');
           });
       });
-      */
-      fs.root.getFile(
-          'file4',
-          {'create': true},
-          expectAsync1((FileEntry e) {
-            expect(e.name, equals('file4'));
-            expect(e.isFile, equals(true));
-          }),
-          (e) {
-            fail('Got file error: ${e.code}');
-          });
-      });
   });
 }