GL is the only implementation of TextureMapper now, so we don't need to have both.
Pull request: https://github.com/WebKit/WebKit/pull/19768
Committed 270048@main (9860d777b101): <https://commits.webkit.org/270048@main> Reviewed commits have been landed. Closing PR #19768 and removing active labels.
<rdar://problem/117788825>