re-add guard to flutter for fuchsia build -- until newer flutter lands

Bug: skia:
Change-Id: I408bc113f5036710c743890de45e286021c6be88
Reviewed-on: https://skia-review.googlesource.com/c/170346
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
1 file changed