`$.utils.replacePhysicalsWithName` does not terminate when passed circular structure

[cpcallen]

It's reasonable enough that this function does not preserve circularity (it's only intended to handle the POJSO equivalent of a JSON value), but it should not recurse infinitely if passed circular data.

[cpcallen]

Tagging this as milestone: launch for now. We should at least verify that the default Thread timeout is sufficient to prevent the server from running out of memory due to infinite recursion.