WebGPU: Obey buffer alignment rules WebGPU buffers require a size aligned to 4 bytes and map buffer offsets aligned to 8 bytes. Hide this requirement in The BufferHelper class by doing the apropriate offsets during buffer creation and map calls. This allows many dEQP tests to run without crashing due to WebGPU buffer creation errors. Bug: angleproject:356399840 Bug: angleproject:42267091 Change-Id: Id71c3b5db31aa712d5a88631efa4897d6205a41d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5748443 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>