fix: [#2045] Replace JSON.parse(JSON.stringify()) with structuredClone()

[TrevorBurnham]

Resolves #2045

This PR uses structuredClone() for deep cloning instead of JSON.parse(JSON.stringify()).

Files changed

• Headers.ts: Clone entries when constructing from another Headers instance
• CSSStyleDeclarationPropertyManager.ts: Clone properties in clone() method
• MediaStreamTrack.ts: Clone CAPABILITIES and SETTINGS constants

[TrevorBurnham]

I believe the CI failures are due to #2022, which is fixed by #2023.

[capricorn86]

Is structuredClone() really faster?

Many benchmarks suggests that JSON.stringify() is much faster for certain objects as it doesn't have to round-trip to the JavaScript engine.

Here are some benchmarks:
https://www.measurethat.net/Benchmarks/Show/18541/0/jsonstringify-vs-structuredclone#latest_results_block

Would be interesting to benchmark with the actual code in Happy DOM.

[TrevorBurnham]

Huh! I'm surprised, but my own checks back up those benchmarks. Hopefully future Node.js versions will improve structuredClone performance. Until then, closing this out.