R1:f8cebdc418e8

Make Differential inline events actually trigger comment preview refreshes

Summary:
Earlier, I made some changes so that when you create or edit an inline, the comment at the bottom of the page updates (even though you didn't fiddle with the stacked actions inputs).

At the last second I broke them by spelling this wrong while cleaning things up, so they didn't actually work. Spell the property correctly ("showPreview", not "shouldPreview").

Also, we have some JS which rewrites "Not Visible" into "View"…