Previously the type was first set to uint8 and then corrected
later in walkrange.

Change-Id: I9e4b597710e8a5fad39dde035df85676bc8d2874
Reviewed-on: https://go-review.googlesource.com/61032
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>