Fix move-watched-dir for MacOS.

runtime/bin/file_system_watcher_macos.cc

 // 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/file_system_watcher.h"
 
 #include <errno.h>  // NOLINT
@@ skipping 249 matching lines @@
   FSEvent e;
   for (int i = 0; i < count; i++) {
     intptr_t bytes = TEMP_FAILURE_RETRY(read(fd, e.bytes, sizeof(e)));
     if (bytes < 0) {
       return DartUtils::NewDartOSError();
     }
     size_t path_len = strlen(e.data.path);
     Dart_Handle event = Dart_NewList(4);
     int flags = e.data.flags;
     int mask = 0;
+    if (flags & kFSEventStreamEventFlagItemRenamed) {
+      if (path_len == 0) {
+        // The moved path is the path being watched.
+        mask |= kDeleteSelf;
+      } else {
+        mask |= kMove;
+      }
+    }
     if (flags & kFSEventStreamEventFlagItemModified) mask |= kModifyContent;
-    if (flags & kFSEventStreamEventFlagItemRenamed) mask |= kMove;
     if (flags & kFSEventStreamEventFlagItemXattrMod) mask |= kModefyAttribute;
     if (flags & kFSEventStreamEventFlagItemCreated) mask |= kCreate;
     if (flags & kFSEventStreamEventFlagItemIsDir) mask |= kIsDir;
     if (flags & kFSEventStreamEventFlagItemRemoved) {
       if (path_len == 0) {
         // The removed path is the path being watched.
         mask |= kDeleteSelf;
       } else {
         mask |= kDelete;
       }
     }
     Dart_ListSetAt(event, 0, Dart_NewInteger(mask));
     Dart_ListSetAt(event, 1, Dart_NewInteger(1));
     Dart_ListSetAt(event, 2, Dart_NewStringFromUTF8(
         reinterpret_cast<uint8_t*>(e.data.path), path_len));
     Dart_ListSetAt(event, 3, Dart_NewBoolean(true));
     Dart_ListSetAt(events, i, event);
   }
   return events;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)