Enforce Low Power Mode / Optimize Video Streaming setting by tone mapping HDR video to SDR
<rdar://problem/100597710>
Pull request: https://github.com/WebKit/WebKit/pull/4938
Committed 255127@main (d11f383c16ed): <https://commits.webkit.org/255127@main> Reviewed commits have been landed. Closing PR #4938 and removing active labels.