Ensure we keep proper height and width settings for SVGs, unless those values don't exist

[dkotter]

Description of the Change

Previously we were setting the height and width of SVGs to be false, which can cause issues in certain places (like within Gutenberg) if they use those values for calculations. Instead, use the height and width values WordPress calculates for those files and if they don't exist for some reason, default those to 100, so we have a proper fallback value.

Closes #18

Alternate Designs

None

Possible Drawbacks

I'm unsure of why we were setting these to false to begin with. The function documentation even mentions we default to 100, but as far as I can tell, that was never happening. I've tested a number of various scenarios and I've not seen any issues with using the calculated height and width instead of using false but there's potential that I missed some scenario.

Verification Process

Follow the reproduction steps listed in #18 to verify the reported issue.

In addition, ensure that any SVG that gets uploaded displays correctly within the admin Media Library, within the attachment single page and when added to a Post or Page.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Changelog Entry

Fixed - Use calculated size for SVGs instead of using false

Credits

[darylldoyle]

This PR looks good to me.

I changed it from 100 to false in version 1.4.5. I feel it's because it was previously setting the width and height to 100px regardless of if the image had dimensions.

If I recall, the image sizes were always being passed as 0, so SVGs were always being rendered with a height and width of 0px. false is definitely incorrect though, so this is better than that.

I'd love to test whether this affects SVGs being rendered on the front end or not as we don't want to introduce a regression where SVGs render with 0px width/height.

[darylldoyle]

Tested locally and looks good to me 🚀