Dot files are a graph format that can be visualized with GraphViz.
Giving a small visualization output can help diagnose problems with
the graph. For example extra edges or incorrect dependencies.

Bug: angleproject:2379
Change-Id: I544cba11c5e33579b06fef2fb41bad60066a64e4
Reviewed-on: https://chromium-review.googlesource.com/1254383
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tobin Ehlis <tobine@google.com>