Describe the bug
Blanking fill is supposed to make a filled planar shape draw behind other geometry belonging to the same element. The principal use case is for text background color. Instead, it can also draw behind geometry belonging to lots of other elements in the same view.

To Reproduce
Steps to reproduce the behavior:

1. Follow the steps in this comment.
2. Observe the house geometry draws in front of the text background.

Expected behavior
The text background should draw in front of the house geometry, but behind the text border and text itself.

Additional context

We adjust the depth of blanking regions backward slightly to put it behind other geometry, but that puts it behind geometry belonging to any element that happens to have a similar non-adjusted depth.
We also draw both the text and the fill in the same render pass (opaque planar), which gives us no opportunity to discard the fill in favor of the text.

We should stop adjusting the depth, and just draw the blanking fill in the non-planar render pass. Then it will be discarded in favor of the element's other geometry.