Reduced memory usage of primitive fields smaller than 4-bytes

Reduced memory used by byte and boolean fields from 4 bytes down to a
single byte and shorts and chars down to two bytes. Fields are now
arranged as Reference followed by decreasing component sizes, with
fields shuffled forward as needed.

Bug: 8135266
Change-Id: I65eaf31ed27e5bd5ba0c7d4606454b720b074752