When using a dynamic uploader we didn't align the offset
that the allocated memory might have already had.
That fixes WriteTexture, WriteBuffer, ClearTexture and
on D3D12 ClearBuffer.
Bug: dawn:512
Change-Id: I64c7511ad6b0d3d6a28a494e1324a10ad4d38091
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/27020
Commit-Queue: Tomek Ponitka <tommek@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>