runtime: fix argument dump in traceback
runtime: fix argument dump in traceback

Was printing words at SP instead of at FP
after shuffle due to nascent flag.

R=r, r2
CC=golang-dev
http://codereview.appspot.com/2316044
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go