Remove reference to onError from file API docs.

runtime/bin/file.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.
 
 
 /**
  * FileMode describes the modes in which a file can be opened.
  */
 class FileMode {
   static final READ = const FileMode._internal(0);
@@ skipping 81 matching lines @@
   int lengthSync();
 
   /**
    * Open the file for random access operations. Returns a
    * [:Future<RandomAccessFile>:] that completes with the opened
    * random access file. RandomAccessFiles must be closed using the
    * [close] method.
    *
    * Files can be opened in three modes:
    *
-   * FileMode.READ: open the file for reading. If the file does not
-   * exist [onError] is called.
+   * FileMode.READ: open the file for reading.
    *
    * FileMode.WRITE: open the file for both reading and writing and
    * truncate the file to length zero. If the file does not exist the
    * file is created.
    *
    * FileMode.APPEND: same as FileMode.WRITE except that the file is
    * not truncated.
    *
    * The default value for [mode] is [:FileMode.READ:].
    */
@@ skipping 255 matching lines @@
         sb.add(" ($osError)");
       }
     } else if (osError != null) {
       sb.add(": osError");
     }
     return sb.toString();
   }
   final String message;
   final OSError osError;
 }