Apply recursion limit in validation

[goto-bus-stop]

The parser has a recursion limit to prevent stack overflows on deeply nested selection sets. Validation has recursion breaks for things that may circularly reference each other. But if you build a chain of thousands of named things that reference each other, you may theoretically be able to cause a stack overflow before the recursion break triggers (before it references back to the original definition).

[qwerdenkerXD]

You're right, here is it.