[Impeller] determine correct behavior of entity pass bounds fractional values. #145180
Description
See also: #144213
We added a roundOut to the bounds of entity passes, that resulted in odd behavior for blurs. This was better on master with the new blurs, but in theory it shouldn't happen.
This is a tracking issue to figure out what the right solution is that doesn't cause flickering of blurs.
FYI @flar