On iOS, we find ourselves in a position where we want to run the same test multiple times of different device types. Our methods of reporting and visualizing results need to support this.
After discussion, this change will only apply to run-webkit-tests when run locally. Infrastructure will never run tests this way.
After more discussions and digging into how this would work, I don't see a particular need for it. Especially given the work that is to be done in <https://bugs.webkit.org/show_bug.cgi?id=192162> and <https://bugs.webkit.org/show_bug.cgi?id=193537>.