Increasing pixel size maintains ratio but other dimension doesn't increase.

[mrwweb]

Describe the bug
Increasing one dimension of an image increases both width and height proportionally. If the feature is going to be included in 5.0 (which I'd rather not, but I doubt that's changing), then the other dimension should update itself.

In reproducing this bug, one quickly runs into #12168 as well.

To Reproduce

1. Insert an image.
2. Select a image size (at the moment I also had to set the image size to 100% for the pixel-sizing to work at all)
3. Increase its size via the width or height pixels settings
4. The image increases in size, but the other pixel dimension does not change.

Expected behavior
Width/height pixel settings remain proportional at all times.

Screenshots

When increasing width, the height does not proportionally increase. When increasing height afterwards, it doesn't impact the image.

Desktop (please complete the following information):
Win 10, WP 5.0-RC1, Firefox 63.0.3, no plugins, Twenty Nineteen

[paaljoachim]

I checked out this issue with Twenty Twenty One.
Image size: Medium
100%
Then began nudging the Width and Height pixels.
Caption moved as the image moved.

I will go ahead and close this issue. Please reopen if it is a mistake.