New pixel test results generated by run-webkit-tests should be platform-specific by default. We already do this for new render tree results.
Just passing through. I haven't actually tested this recently but this might already be the case. See expectedDirectoryForTest in old-run-webkit-tests: sub expectedDirectoryForTest($;$;$)
Yes, I believe this is fixed in the normal case. I think it's still wrong in the layoutTestController.dumpAsText(true) case (where a dumpAsText test has pixel results).