R1:6c43d1d52cbd

Remove "willRenderTimeline()" from ApplicationTransactionInterface

Summary:
Depends on D19914. Ref T11351. Some of the Phoilo rabbit holes go very deep.

`PhabricatorApplicationTransactionInterface` currently requires you to implement `willRenderTimeline()`. Almost every object just implements this as `return $timeline`; only Pholio, Diffusion, and Differential specialize it. In all cases, they are specializing it mostly to render inline comments.

The actual implementations are a bit of a weird mess and…