Unused CSS rule should allow dialog[open]

[leaysgur]

Describe the bug

Same as #5421 , but for dialog element.

<dialog>Hello</dialog>

<style>
	dialog[open] {
		display: grid;
	}
</style>

Currently, this code is warned as unused CSS.

I'm willing to submit a PR later. 👉🏻 #7495

Reproduction

Logs

No response

System Info

System:
    OS: macOS 12.3.1
    CPU: (4) x64 Intel(R) Core(TM) i7-5557U CPU @ 3.10GHz
    Memory: 476.07 MB / 16.00 GB
    Shell: 5.8 - /usr/local/bin/zsh
  Binaries:
    Node: 16.13.1 - ~/.volta/tools/image/node/16.13.1/bin/node
    npm: 8.1.2 - ~/.volta/tools/image/node/16.13.1/bin/npm
    Watchman: 2021.12.27.00 - /usr/local/bin/watchman
  Browsers:
    Chrome: 102.0.5005.27
    Firefox: 99.0.1
    Safari: 15.4
    Safari Technology Preview: 15.4
  npmPackages:
    rollup: ^1.27.14 => 1.27.14

### Severity

annoyance

[Conduitry]

Looking at the REPL, this doesn't appear to have been fixed. I'm not sure why, since the test passed, and this looks like an obvious extension of the mechanism we were already using for details[open].

[Conduitry]

I'm not sure what was happening. Weirdness on unpkg's end maybe? Looks good now.