Fix File:copy FD leak, and add file-closes to some tests.

tests/standalone/io/file_input_stream_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.
 // Testing file input stream, VM-only, standalone test.
 
 import "dart:convert";
 import "dart:io";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
@@ skipping 215 matching lines @@
   test(-1, null);
   test(100, 99);
   test(null, -1);
 }
 
 
 void testStringLineSplitterEnding(String name, int length) {
   String fileName = getFilename("tests/standalone/io/$name");
   // File contains 10 lines.
   File file = new File(fileName);
-  Expect.equals(length, file.openSync().lengthSync());
+  Expect.equals(length, file.lengthSync());
   var lineStream = file.openRead()
     .transform(UTF8.decoder)
     .transform(new LineSplitter());
   int lineCount = 0;
   lineStream.listen(
       (line) {
         lineCount++;
         Expect.isTrue(lineCount <= 10);
         if (line[0] != "#") {
           Expect.equals("Line $lineCount", line);
@@ skipping 12 matching lines @@
   testInputStreamDelete();
   testInputStreamAppend();
   testInputStreamOffset();
   testInputStreamBadOffset();
   // Check the length of these files as both are text files where one
   // is without a terminating line separator which can easily be added
   // back if accidentally opened in a text editor.
   testStringLineSplitterEnding("readline_test1.dat", 111);
   testStringLineSplitterEnding("readline_test2.dat", 114);
 }