dart:io | Add asynchronous Link.create implementation.

runtime/bin/file.h

 // 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.
 
 #ifndef BIN_FILE_H_
 #define BIN_FILE_H_
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ skipping 59 matching lines @@
     kTruncateRequest = 9,
     kLengthRequest = 10,
     kLengthFromPathRequest = 11,
     kLastModifiedRequest = 12,
     kFlushRequest = 13,
     kReadByteRequest = 14,
     kWriteByteRequest = 15,
     kReadRequest = 16,
     kReadListRequest = 17,
     kWriteListRequest = 18,
-    kDeleteLinkRequest = 19
+    kCreateLinkRequest = 19,
+    kDeleteLinkRequest = 20
   };
 
   ~File();
 
   // Read/Write attempt to transfer num_bytes to/from buffer. It returns
   // the number of bytes read/written.
   int64_t Read(void* buffer, int64_t num_bytes);
   int64_t Write(const void* buffer, int64_t num_bytes);
 
   // ReadFully and WriteFully do attempt to transfer num_bytes to/from
@@ skipping 66 matching lines @@
 
   // FileHandle is an OS specific class which stores data about the file.
   FileHandle* handle_;  // OS specific handle for the file.
 
   static NativeService file_service_;
 
   DISALLOW_COPY_AND_ASSIGN(File);
 };
 
 #endif  // BIN_FILE_H_