Popover chevron misplaced when on left or right edge of the bubble

[JeffryBooher]

You should notice there is a gap between the bubble and the chevron

[JeffryBooher]

The bubble probably needs to be nudged over about 5px in either scenario.

[redmunds]

Yes, this is the same issue that's causing unit test to fail in #7272.

[JeffryBooher]

I think it's a problem with the popover API. It shouldn't place the chevron so close to the edge of the bubble regardless -- 7272 is failing because the bubble's right edge is outside the editor.

[redmunds]

Bug filer also did review, so closing.