TGraphTraverser is a class that does nothing by itself so the for loop
was a noop statement and has been for at least two years (since
17732823, didn't check earlier).

BUG=angleproject:591

Change-Id: I1919059fcb8987c2f043a71fed6223e16bc014d8
Reviewed-on: https://chromium-review.googlesource.com/316600
Tryjob-Request: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>