Close a _FileInputStream only immediately before onClosed is called, so .closed returns false befor…

tests/standalone/io/file_test.dart

 // Copyright (c) 2012, 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:io");
 #import("dart:isolate");
 
 class MyListOfOneElement implements List {
@@ skipping 208 matching lines @@
         bytesRead = input.readInto(inputBuffer, offset: position,
                                    len: inputBuffer.length - position);
         position += bytesRead;
         // The buffer is large enough to hold all available data.
         // So there should be no data left to read.
         Expect.equals(0, input.available());
         bytesRead = input.readInto(inputBuffer, offset: position,
                                    len: expectedLength - position);
         Expect.equals(0, bytesRead);
         Expect.equals(0, input.available());
+        Expect.isFalse(input.closed);
       };
       input.onClosed = () {
         Expect.equals(0, input.available());
         Expect.isTrue(input.closed);
         input.close();  // This should be safe to call.
 
         Expect.equals(expectedLength, position);
         for (int i = 0; i < position; ++i) {
           Expect.equals(buffer[i % buffer.length], inputBuffer[i]);
         }
@@ skipping 977 matching lines @@
       testWriteVariousLists();
       testDirectory();
       testDirectorySync();
     });
   }
 }
 
 main() {
   FileTest.testMain();
 }