The flag for running WebKit1 tests is documented as running DumpRenderTree instead of WebKitTestRunner. If you don't already know that means WK1 you may not be able to figure out how to run WK1 tests.
<rdar://problem/100623840>
Pull request: https://github.com/WebKit/WebKit/pull/4864
Committed 255037@main (fa95526169f5): <https://commits.webkit.org/255037@main> Reviewed commits have been landed. Closing PR #4864 and removing active labels.