And have have SourceBufferPrivate::buffered() return a reference as it can never be null
<rdar://problem/106883787>
Actually, SourceBufferPrivate::m_buffered should be a PlatformTimeRanges instead as using a TimeRanges there is a layering violation
Pull request: https://github.com/WebKit/WebKit/pull/11679
Committed 261829@main (e99dba48f4a7): <https://commits.webkit.org/261829@main> Reviewed commits have been landed. Closing PR #11679 and removing active labels.