And not implemented on Windows.
Pull request: https://github.com/WebKit/WebKit/pull/10301
Committed 260469@main (f56ebe32845a): <https://commits.webkit.org/260469@main> Reviewed commits have been landed. Closing PR #10301 and removing active labels.
<rdar://problem/105613555>
Re-opening for pull request https://github.com/WebKit/WebKit/pull/15751
Test gardening commit 265966@main (967b2df6fa4a): <https://commits.webkit.org/265966@main> Reviewed commits have been landed. Closing PR #15751 and removing active labels.
*** Bug 257904 has been marked as a duplicate of this bug. ***