Fix #2859. Display milestones in the right order

[davidcardd1]

This PR fixes https://github.com/GoogleChrome/chromium-dashboard/issues/2859

I changed the order in which OriginTrial milestones are shown (now the start milestones show before the end)

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[jrobbins]

We can't accept this without the CLA.

[DanielRyanSmith]

This has been fixed in a recent PR