More work on upb_def.
More work on upb_def.

tempbottle/upb,bsn069/upb,bsn069/upb,tbetbetbe/upb,tbetbetbe/upb,tbetbetbe/upb,tempbottle/upb,bsn069/upb,bsn069/upb,tbetbetbe/upb,tempbottle/upb,tempbottle/upb,tempbottle/upb,bsn069/upb,tbetbetbe/upb