Enable webgl/2.0.y/conformance2/extensions/webgl-stencil-texturing.html after ANGLE update
<rdar://problem/117586239>
Pull request: https://github.com/WebKit/WebKit/pull/19639
Test gardening commit 269921@main (4c9e9a775c92): <https://commits.webkit.org/269921@main> Reviewed commits have been landed. Closing PR #19639 and removing active labels.