Another fix for -Wc++11-narrowing. Bug: chromium:1216696 Change-Id: I65955fe818917a1909c3d1af391718aaa82652bb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2965535 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>