Change Mac OS to OS X in dart:io dartdoc

sdk/lib/io/file.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.
 
 part of dart.io;
 
 /**
  * The modes in which a File can be opened.
  */
 class FileMode {
@@ skipping 711 matching lines @@
    * specified, the full file is locked, If only `start` is specified
    * the file is locked from byte position `start` to the end of the
    * file, no matter how large it grows. It is possible to specify an
    * explicit value of `end` which is past the current length of the file.
    *
    * To obtain an exclusive lock on a file it must be opened for writing.
    *
    * *NOTE* file locking does have slight differences in behavior across
    * platforms:
    *
-   * On Linux and Mac OS this uses advisory locks, which have the
+   * On Linux and OS X this uses advisory locks, which have the
    * surprising semantics that all locks associated with a given file
    * are removed when *any* file descriptor for that file is closed by
    * the process. Note that this does not actually lock the file for
    * access. Also note that advisory locks are on a process
    * level. This means that several isolates in the same process can
    * obtain an exclusive lock on the same file.
    *
    * On Windows the regions used for lock and unlock needs to match. If that
    * is not the case unlocking will result in the OS error "The segment is
    * already unlocked".
@@ skipping 12 matching lines @@
    * specified, the full file is locked, If only `start` is specified
    * the file is locked from byte position `start` to the end of the
    * file, no matter how large it grows. It is possible to specify an
    * explicit value of `end` which is past the current length of the file.
    *
    * To obtain an exclusive lock on a file it must be opened for writing.
    *
    * *NOTE* file locking does have slight differences in behavior across
    * platforms:
    *
-   * On Linux and Mac OS this uses advisory locks, which have the
+   * On Linux and OS X this uses advisory locks, which have the
    * surprising semantics that all locks associated with a given file
    * are removed when *any* file descriptor for that file is closed by
    * the process. Note that this does not actually lock the file for
    * access. Also note that advisory locks are on a process
    * level. This means that several isolates in the same process can
    * obtain an exclusive lock on the same file.
    *
    * On Windows the regions used for lock and unlock needs to match. If that
    * is not the case unlocking will result in the OS error "The segment is
    * already unlocked".
@@ skipping 90 matching lines @@
       sb.write(": $osError");
       if (path != null) {
         sb.write(", path = '$path'");
       }
     } else if (path != null) {
       sb.write(": $path");
     }
     return sb.toString();
   }
 }