Show file size on admin/reports/xhprof (esp if path is missing)

Sometimes in the list on admin/reports/xhprof the path shows up as empty.

This is a problem of its own, but it would help to also show the file size of the output file, for two reasons:
1. If you have no path, you have at least some criterion to figure out which *might* be the request you are looking for.
2. Even with the path displayed, you now have a good indicator which requests are more expensive. In many cases, bigger file size = more time spent.

Of course other meta information could also be useful, it if is easy to extract.