Bug: Camelcase 'allowFullScreen' doesn't work when 'allow' attribute is set

[masserra]

Problem

Initially I was going to raise a bug simply stating the camelcase version (allowFullScreen) wouldn't work whilst the lowercase version (allowfullscreen) would.

After a few more tests I discovered that the camelcase 'allowFullScreen' doesn't work when 'allow' attribute is set.

Further testing showed that it doesn't add a ; when concatenating fullscreen with the existing allow string, resulting in two allows separated by a space which seems like it's not an option.

Test examples

See code snippets below followed by screenshots of its output.

<Iframe
      url={url}
      width="100%"
      height={height || "350"}
      styles={{
        ...(!height && { aspectRatio: "16 / 9" })
      }}
      display="block"
      position="relative"
      frameBorder={0}
      allowfullscreen
      loading="lazy"
      allow="accelerometer; autoplay; clipboard-write; encrypted-media; fullscreen; gyroscope; picture-in-picture"
/>

The code above using lowercase allowfullscreen (which works) outputs this:

---

<Iframe
      url={url}
      width="100%"
      height={height || "350"}
      styles={{
        ...(!height && { aspectRatio: "16 / 9" })
      }}
      display="block"
      position="relative"
      frameBorder={0}
      allowFullScreen
      loading="lazy"
      allow="accelerometer; autoplay; clipboard-write; encrypted-media; fullscreen; gyroscope; picture-in-picture"
/>

The code above using camelcase allowFullScreen (which doesn't work) outputs this:

(As you can see, not only doesn't add a ; after the fullscreen directive, it also leaves lost orphan ; in between from where it initially was located)

---

<Iframe
      url={url}
      width="100%"
      height={height || "350"}
      styles={{
        ...(!height && { aspectRatio: "16 / 9" })
      }}
      display="block"
      position="relative"
      frameBorder={0}
      allowFullScreen
      loading="lazy"
/>

The code above removing the allow property and using camelcase allowFullScreen (which works) outputs the following as expected:

(As you can see, because it has no allow it doesn't have a problem with not having a ; therefore it works)