Row-major test: Clarify std140's stride calculation
Row-major test: Clarify std140's stride calculation

Bug: angleproject:3830
Change-Id: I5fa213927b609ef33c729ded5d42add8f148dcb1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2012622
Reviewed-by: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle