Fix diff commit list complexity icons in Chrome

Review Request #7292 — Created May 7, 2015 and submitted — Latest diff uploaded

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dvcs
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Reviewers

The diff complexity icons in the DiffCommitList were not correctly
rendering in Chrome previously. This has been rectified.

Removed some dead CSS as we no longer use the RB icon spinner in the
commit lists, but instead use the FontAwesome spinner.

Checked appearance in both Chrome and Firefox.