IllegalValueError seems to be not a known DOMException

In section [5.3](http://webtiming.github.io/timingobject/#x5-3-process-an-update-operation) of the spec, it says that an `IllegalValueError` should be thrown under certain conditions. However I couldn't find a definition of an `IllegalValueError` and it seems to be not a known DOMException. At least according to this list: https://heycam.github.io/webidl/#idl-DOMException-error-names