Previously, when `rect` was taller than it was wide, the spinner would
render far outside the given rectangle. Now, it always renders inside
the smaller of the two dimensions.
I noticed this when upgrading from 0.30 to 0.32. I have an image that's
significantly taller than it is wide. In 0.32, when the image is
loading, it shows the spinner. Since the spinner radius is determined
solely based on rectangle height, the spinner ends up far too wide and
covers other elements.
* [x] I have followed the instructions in the PR template
0abeccebc9