Store the length of originally requested array size prior to trimming.

This change adds GetRequestedArrayLength() method to both single and double
vector ref tokens, which returns the length of the requested array size prior
to trimming of the trailing empty cell region.

Change-Id: Iaba96fa2ea4ff3c8bccb0bc86fa4f1525e2f45fb
Ensure that numeric array storage is aligned to 256-byte boundary.

OpenCL devices require this else we would get a performance hit.

Change-Id: I6b1db6320fa84f933b6446022a0fd02ba267bf21