dart:io | Revert addition of Link class, because it conflicts with a Link class in dart2js.

runtime/bin/file_macos.cc

 // 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/file.h"
 
 #include <errno.h>  // NOLINT
@@ skipping 143 matching lines @@
 
 bool File::Create(const char* name) {
   int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CREAT, 0666));
   if (fd < 0) {
     return false;
   }
   return (close(fd) == 0);
 }
 
 
-bool File::CreateLink(const char* name, const char* target) {
-  int status = TEMP_FAILURE_RETRY(symlink(target, name));
-  return (status == 0);
-}
-
-
 bool File::Delete(const char* name) {
   int status = TEMP_FAILURE_RETRY(remove(name));
   if (status == -1) {
     return false;
   }
   return true;
 }
 
 
 off_t File::LengthFromPath(const char* name) {
@@ skipping 90 matching lines @@
     stat_success = TEMP_FAILURE_RETRY(lstat(pathname, &entry_info));
   }
   if (stat_success == -1) return File::kDoesNotExist;
   if (S_ISDIR(entry_info.st_mode)) return File::kIsDirectory;
   if (S_ISREG(entry_info.st_mode)) return File::kIsFile;
   if (S_ISLNK(entry_info.st_mode)) return File::kIsLink;
   return File::kDoesNotExist;
 }
 
 #endif  // defined(TARGET_OS_MACOS)