Expose toggles for various WebCore technologies including: FileReader, SpeechSynthesis & Fetch.
<rdar://problem/100318108>
Pull request: https://github.com/WebKit/WebKit/pull/4625
Committed 254804@main (676cef498e74): <https://commits.webkit.org/254804@main> Reviewed commits have been landed. Closing PR #4625 and removing active labels.