In the process, add a utility functions to automate printing out comma-separated
lists. Also make sure that the << operator applies to "const Type&" rather than
"const Type*" for consistency elsewhere and generally just good practice.

Bug: v8:7793
Change-Id: I488e8383c4a9496552e63601738d6bcca0ca6e80
Reviewed-on: https://chromium-review.googlesource.com/1111854
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54038}