STEPS TO REPRODUCE: 1. Find a test that times out 2. $ Tools/Scripts/run-webkit-tests --no-timeout path/to/test.html 3. Open a Safari that can remote-inspect (i.e., a shipped version) 4. WebKitTestRunner should be an inspect target, but it is not listed. It seems that there is a missing entitlement or something like that. However, it's possible to attach to WKTR using Xcode. It doesn't appear to be built using app sandbox or anything like that, so there may be some additional work to build in this way. If you know more about what needs to be done, please comment on this bug or message me!