Update `DEPS` to pull in linter `0.1.30`.

[pq]

A few items (not ordered):

• tag a 0.1.30 branch
• migrate DEPS back to using tags rather than versions
• verify that name changes (search box match result presentation issues (was: dart editor - no way to navigate to a class) #489) won't break internal users (FYI @srawlins, @matanlurey)

[pq]

I believe @srawlins did a spot-check on renames...

[srawlins]

Erm, I don't remember doing that.

[pq]

Sorry @srawlins, I think @alexeieleusis eye-balled this and I got mixed up. Anyhoo, I trust you'll tell me if we got it wrong! 😉