Update the support information for `structuredClone` (PR 14392 follow-up)
Update the support information for `structuredClone` (PR 14392 follow-up)

When the `structuredClone` polyfill was added, the support information in Safari was unclear. Given that an actual version *number* is now available, see below, it seems like a good idea to update the comment accordingly.

https://developer.mozilla.org/en-US/docs/Web/API/structuredClone#browser_compatibility

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