Style violation cleanup for IntermTraverse.cpp

Per suggested by kbr in https://codereview.appspot.com/14366043/, we clean up the stype violation in a separate CL.

BUG=
TEST=no behavioral change
TBR=kbr@chromium.org

Review URL: https://codereview.appspot.com/14371043

Change-Id: I27e15f632eff3a9d0d22ae955b5a952793128661
Reviewed-on: https://chromium-review.googlesource.com/178991
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>