Use more smart pointers in Source/WebKit/WebProcess/cocoa/TextTrackRepresentationCocoa.mm.
Pull request: https://github.com/WebKit/WebKit/pull/16731
Committed 266949@main (fd292c9a79f1): <https://commits.webkit.org/266949@main> Reviewed commits have been landed. Closing PR #16731 and removing active labels.
<rdar://problem/113975774>