Don't depend on libdart_io in run_vm_tests and gen_snapshot.

runtime/bin/builtin_natives.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 <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "include/dart_api.h"
 
@@ skipping 43 matching lines @@
   V(File_Delete, 1)                                                            \
   V(File_DeleteLink, 1)                                                        \
   V(File_Rename, 2)                                                            \
   V(File_Copy, 2)                                                              \
   V(File_RenameLink, 2)                                                        \
   V(File_ResolveSymbolicLinks, 1)                                              \
   V(File_OpenStdio, 1)                                                         \
   V(File_GetStdioHandleType, 1)                                                \
   V(File_GetType, 2)                                                           \
   V(File_AreIdentical, 2)                                                      \
-  V(FileSystemWatcher_CloseWatcher, 1)                                         \
-  V(FileSystemWatcher_GetSocketId, 2)                                          \
-  V(FileSystemWatcher_InitWatcher, 0)                                          \
-  V(FileSystemWatcher_IsSupported, 0)                                          \
-  V(FileSystemWatcher_ReadEvents, 2)                                           \
-  V(FileSystemWatcher_UnwatchPath, 2)                                          \
-  V(FileSystemWatcher_WatchPath, 4)                                            \
   V(Logger_PrintString, 1)
 
 BUILTIN_NATIVE_LIST(DECLARE_FUNCTION);
 
 static struct NativeEntries {
   const char* name_;
   Dart_NativeFunction function_;
   int argument_count_;
 } BuiltinEntries[] = {
   BUILTIN_NATIVE_LIST(REGISTER_FUNCTION)
@@ skipping 38 matching lines @@
     // interrupt.
     fprintf(stdout, "%s\n", Dart_GetError(result));
   } else {
     fprintf(stdout, "%.*s\n", static_cast<int>(length), chars);
   }
   fflush(stdout);
 }
 
 }  // namespace bin
 }  // namespace dart