Use correct packing for Metal uniform arrays.

In Metal, the alignment requirements for float and float2 arrays allow
them to be packed tightly. Packing them loosely was uploading the
data to the wrong locations in GPU memory.

Bug: skia:8243
Change-Id: Ie09edf3363a1f3cefc1da73aa85c4352f0fbedf0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211341
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
2 files changed