Output shows floating point numbers when leaks are inconsistent

[nolanlawson]

If a page is leaking nodes / listeners at an irregular rate (e.g. for 7 iterations, a node leaked 9 times), then the CLI will show a floating point number (e.g. 1.2857142857142858 per iteration).

I don't really want to use the same "it must be exactly 7 iterations" logic for DOM nodes or event listeners, because in those cases, a leak is a leak, but maybe the output can be a bit cleaner.