Add 'buffer,resource_offset' to createBindGroup.spec.ts (#1825)
Add 'buffer,resource_offset' to createBindGroup.spec.ts (#1825)

The specification says that the resource offset should be a
multiple of limits.[minUniformBufferOffsetAlignment|minStorageBufferOffsetAlignment]
if the BindGroup entry defines buffer and the buffer's type is
[uniform|storage|read-only-storage].

Issue: #884
gpuweb/cts,gpuweb/cts,gpuweb/cts