When horizontal scrollbars are present, text should still only grow to visible parent width

[kkoreilly]

Describe the bug

Horizontal scrollbars should not mean that all of the text has to go off of the screen. We may also want to make a similar fix for Grow, and for parent-based sizing (#1517).

How to reproduce

Add a widget that forces horizontal scrolling, and then observe that all of the text now goes off the screen.

Example code

Relevant output

Platform

macOS