bug 250249 removes it from DeprecatedGlobalSettings, but if the preference does nothing, it should be entirely removed.
Youenn confirmed this is unused
<rdar://problem/104021962>
Pull request: https://github.com/WebKit/WebKit/pull/8389
Committed 258655@main (bc2b6ffeef9e): <https://commits.webkit.org/258655@main> Reviewed commits have been landed. Closing PR #8389 and removing active labels.