Add version_added for ReadableStreamBYOB*

[saschanaz]

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• Summarize your changes
• Data: link to resources that verify support information (such as browser's docs, changelogs, source control, bug trackers, and tests)
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• Link to related issues or pull requests, if any: closes api.ReadableStreamBYOBReader - Supported on Chrome/Edge #10445

[ddbeck]

Are sure about these? A couple (admittedly very shallow) searches seem to turn up some evidence that these aren't abandoned features:
https://bugs.chromium.org/p/chromium/issues/detail?id=614302&q=ReadableByteStreamController&can=2
https://bugzilla.mozilla.org/show_bug.cgi?id=1507945

It'd be good to take a closer look—perhaps do a little testing to more strongly confirm non-implementation—before merging this.

[domenic]

Indeed, these are currently being implemented in Chromium, targeting a release or two from now.

[ddbeck]

The status entry says this also shipped on WebView. Would you mind setting the same version for that browser too? https://chromestatus.com/feature/4535319661641728 Thank you!

[ddbeck]

Thank you! 🎉