Auto merge of #25548 - pshaughn:docnamedgetter, r=jdm

Add SupportedPropertyNames to Document (also fix iframe getting)

Existing test of named-getting an iframe now succeeds. I added a new test for Object.getOwnPropertyNames(document) based on my understanding of the spec; that test could use a second opinion.

UPDATE: This was trying to do too many things in one PR as originally submitted. It is now using #25572 as a base, and I suggest reviewing that PR before this one to avoid duplicating review effort.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #7273 for all implemented named getters, fix #25146, and fix the iframe case only of #25145.

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- [X] There are tests for these changes

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