Translator: Validate precision for function args In fragment shaders, float does not have a default precision. Any declaration of this type must therefore specify the precision if a default one is not provided. This was not validated for function arguments. Bug: chromium:1255089 Change-Id: I0d17e226ec88610692ec7dd18793cf4d471f12e7 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3226314 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>