Fix errors in previous commit

tests/standalone/io/file_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.
 //
 // Dart test program for testing file I/O.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:collection';
 import 'dart:io';
@@ skipping 698 matching lines @@
     RandomAccessFile openedFile = file.openSync(mode: WRITE);
     openedFile.writeFromSync(buffer, 0, 10);
     Expect.equals(10, openedFile.lengthSync());
     openedFile.truncateSync(5);
     Expect.equals(5, openedFile.lengthSync());
     openedFile.closeSync();
     file.deleteSync();
     Expect.isFalse(file.existsSync());
   }
 
-  static void testReadInto() async {
+  static testReadInto() async {
     asyncTestStarted();
     File file = new File(tempDirectory.path + "/out_read_into");
 
     var openedFile = await file.open(mode: WRITE);
     await openedFile.writeFrom(const [1, 2, 3]);
 
     await openedFile.setPosition(0);
     var list = [null, null, null];
     Expect.equals(3, await openedFile.readInto(list));
     Expect.listEquals([1, 2, 3], list);
 
     read(start, end, length, expected) async {
       var list = [null, null, null];
       await openedFile.setPosition(0);
       Expect.equals(length, await openedFile.readInto(list, start, end));
       Expect.listEquals(expected, list);
       return list;
     }
 
     await read(0, 3, 3, [1, 2, 3]);
     await read(0, 2, 2, [1, 2, null]);
     await read(1, 2, 1, [null, 1, null]);
     await read(1, 3, 2, [null, 1, 2]);
     await read(2, 3, 1, [null, null, 1]);
+    await read(0, 0, 0, [null, null, null]);
 
     asyncTestDone("testReadInto");
   }
 
   static void testReadIntoSync() {
     File file = new File(tempDirectory.path + "/out_read_into_sync");
 
     var openedFile = file.openSync(mode: WRITE);
     openedFile.writeFromSync(const [1, 2, 3]);
 
     openedFile.setPositionSync(0);
     var list = [null, null, null];
     Expect.equals(3, openedFile.readIntoSync(list));
     Expect.listEquals([1, 2, 3], list);
 
     read(start, end, length, expected) {
       var list = [null, null, null];
       openedFile.setPositionSync(0);
       Expect.equals(length, openedFile.readIntoSync(list, start, end));
       Expect.listEquals(expected, list);
       return list;
     }
 
     read(0, 3, 3, [1, 2, 3]);
     read(0, 2, 2, [1, 2, null]);
     read(1, 2, 1, [null, 1, null]);
     read(1, 3, 2, [null, 1, 2]);
     read(2, 3, 1, [null, null, 1]);
+    read(0, 0, 0, [null, null, null]);
   }
 
-  static void testWriteFrom() async {
+  static testWriteFrom() async {
     asyncTestStarted();
     File file = new File(tempDirectory.path + "/out_write_from");
 
     var buffer = const [1, 2, 3];
     var openedFile = await file.open(mode: WRITE);
 
     await openedFile.writeFrom(buffer);
     var result = []..addAll(buffer);;
 
     write([start, end]) async {
-      await openedFile.writeFrom(buffer, start, end);
+      var returnValue = await openedFile.writeFrom(buffer, start, end);
+      Expect.identical(openedFile, returnValue);
       result.addAll(buffer.sublist(start, end));
     }
     await write(0, 3);
     await write(0, 2);
     await write(1, 2);
     await write(1, 3);
     await write(2, 3);
+    await write(0, 0);
 
     var bytesFromFile = await file.readAsBytes();
     Expect.listEquals(result, bytesFromFile);
     asyncTestDone("testWriteFrom");
   }
 
   static void testWriteFromSync() {
     File file = new File(tempDirectory.path + "/out_write_from_sync");
 
     var buffer = const [1, 2, 3];
     var openedFile = file.openSync(mode: WRITE);
 
     openedFile.writeFromSync(buffer);
     var result = []..addAll(buffer);;
 
     write([start, end]) {
-      openedFile.writeFromSync(buffer, start, end);
+      var returnValue = openedFile.writeFromSync(buffer, start, end);
       result.addAll(buffer.sublist(start, end));
     }
     write(0, 3);
     write(0, 2);
     write(1, 2);
     write(1, 3);
     write(2, 3);
 
     var bytesFromFile = file.readAsBytesSync();
     Expect.listEquals(result, bytesFromFile);
@@ skipping 634 matching lines @@
       testLastModified();
       testDoubleAsyncOperation();
       asyncEnd();
     });
   }
 }
 
 main() {
   FileTest.testMain();
 }