reflect: test to make sure big Zero()-obtained objects are really zero.
reflect: test to make sure big Zero()-obtained objects are really zero.

Update issue 6876.

R=dave, bradfitz
CC=golang-dev
https://codereview.appspot.com/36370043

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang