CONSOLE MESSAGE: GPUDevice.createBuffer(): Buffer cannot have both MAP_READ and MAP_WRITE usage!

PASS GPUBuffers can be created with both read-only and STORAGE usages. 
PASS unmap on already unmapped, mappable GPUBuffer should not generate error. 
PASS GPUBuffer created via createBufferMapped cannot be remapped. 
PASS GPUBufferDescriptor with both MAP_READ and MAP_WRITE usage should fail. 
PASS Too-large GPUBufferDescriptor size should fail with out-of-memory error. 
PASS mapReadAsync on non-MAP_READ GPUBuffer should fail. 
PASS mapWriteAsync on non-MAP_WRITE GPUBuffer should fail. 
PASS unmap on non-mappable GPUBuffer should fail. 
PASS createBufferMapped: non-4-byte-aligned GPUBufferDesriptor size should fail. 
PASS Any method call on an invalid GPUBuffer should fail. 
PASS Any method call on a destroyed GPUBuffer should fail.