UI text is sometimes shifted to the left of where it should be

## Bevy version

`cf4bfb649dd06b4b6826424dbbc4efea9a6d924a`

## What you did

- Removed the `padding` from the sidebar in the `grid` example (`examples/ui/grid.rs`)
- Ran the `grid` example

## What went wrong

Text in the sidebar overflows out of the sidebar element on the left hand side. The exact amount it overflows by depends on how wide the sidebar is (which can be changed by resizing the window). Note: text is left-aligned.

## What should have happened

The text should be entirely contained within the node (unless the width is made so small that a single word cannot fit, but it that case it should overflow to the right not the left).

## Additional information

I suspect this is a bug in `glyph_brush_layout`, but I'm not sure about that.