This change does some visual polish to the display of commits on the

review request:

On the review request page, fixed the spacing between the "Commits"

  label and the table (before there was none).
On the diff viewer page, hid the "Commits" field entirely, since its

  content overlaps with that of the commit selector table. This was

  especially confusing when the latest revision had a different set of

  commits than the revision being viewed.
Fixed spacing of the different sections on the diff viewer page:

  various diff "fields" had equal spacing above and below, and didn't

  provide enough whitespace to really associate the label with the

  item.

Viewed the reviews and diff viewer pages and saw that everything looked

much nicer.