CONSOLE MESSAGE: GPUBuffer.mapWriteAsync(): Invalid operation!
CONSOLE MESSAGE: GPUBuffer.mapWriteAsync(): Invalid operation!

PASS Map write, unmap, and destroy a GPUBuffer. 
PASS Reject a map write on a buffer not created with MAP_WRITE usage. 
PASS Reject a map write on a mapped GPUBuffer. 
PASS Reject a pending map write if GPUBuffer is unmapped.