full-sized GIF in floated image block won't resize properly

[jcklpe]

Describe the bug

Image appears smaller in gutenberg editor but is larger when post is previewed before publishing.

To reproduce

1. I insert a gif as an image block into a post, and set it to float right.
2. I set the size of the image to Full Size because that is required in order to show the gif animation properly.
3. I then set the image dimensions to 25%. This properly rescales the full sized animating gif within the gutenberg editor
4. But when I hit preview the image is MASSIVE.

It also does not appear from checking the image styling in the inspector to be adding any additional styles based on size. I don't know why that is.

Expected behavior
I expect the gutenberg editor and the previewed post to both styled correctly.

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu 18.04
• Browser: firefox
• Version: newest non nightly build.

Additional Notes:

• This appears to only be an issue with gifs, as the jpegs properly resize. I checked with the "full sized" version of the jpegs just like with the gifs so I don't think it's the image version being used that's the issue.

[jcklpe]

To make this clear, this isn't a theme issue because this previously worked. There was some change in Gutenberg that broke this. What was that change?

The theme is also only calling post content, and there's no apparent styling on the relevant elements that is resulting in the default wordpress post content classes from doing their thing.

[talldan]

Hi @jcklpe. Thanks for reporting this. The issue was discussed during a triage meeting in the core-editor slack channel (the link will require a slack account if you don't have one - https://wordpress.slack.com/archives/C02QB2JS7/p1584597301019700).

A couple of us were unable to reproduce the issue. I'll close the issue for now. I realize some time has passed, if you're still experiencing the problem drop a reply in the issue and we can take a look into what might be happening.

[jcklpe]

@talldan I figured out the basic problem and logged a bug on it here:
#18122
and here I suggested the solution.
#18276

There is at least one more link where I actually commented on the new code that was merged in that changed things, and had a discussion with the dev who implemented it and why and reading that might help provider further context.

Basically the issue had to do with a change in how floated images' html was wrapped.