testing: fix time reported for failing tests. t.ns was hanging after recent changes.
testing: fix time reported for failing tests.
t.ns was hanging after recent changes.

R=gri, rsc
CC=golang-dev
http://codereview.appspot.com/5237044

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