R1:3244324cb1ab

Fix comment box borders in timelines after Phriction commenting

Summary:
Ref T13202. In D19660, I added comments to Phriction and tweaked some CSS.

One of these tweaks was getting rid of an extra border which was rendering under the comment area. However, I took off too much and ended up removing borders from other applications.

I think we don't actually need this `setNoBorder()` stuff after all -- a later change was sufficient to stop the actual border I was trying to get rid of from rendering. So this…