image-cdn: Avoid fatal on bad img width/height

[anomiex]

Proposed changes:

If the <img> tag has a value for width or height that's neither an integer nor a percentage, this will cause a fatal error when the value is attempted to be used as an integer. Add validation to avoid this.

This was introduced in #32700, the implicit validation included in the parameter extraction regex was lost when it was switched to use the HTML API.

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Jetpack product discussion

p1725378345801409/1725375599.111769-slack-C01U2KGS2PQ

Does this pull request change what data or activity we track or use?

No

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[github-actions]

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[github-actions]

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[ice9js]

The code looks ok, but it's difficult to tell if that's actually all of it and the desired behavior without additional context and/or testing instructions.

cc @dilirity since you worked on merging #32700 as well.

[dmsnell]

Thanks!

[dilirity]

Wow. This slipped somehow. Thanks for quickly addressing it.