Make GCGLOwned* to normal classes. The classes are a bit hard to understand and use when they are generate by preprocessor.
<rdar://problem/121913559>
Pull request: https://github.com/WebKit/WebKit/pull/23496
Committed 273735@main (a60ae9fc6721): <https://commits.webkit.org/273735@main> Reviewed commits have been landed. Closing PR #23496 and removing active labels.