Applying modification pattern in #385 to FilteringParserDelegate#_nextToken2

[T45K]

In #385, FilteringParserDelegate#nextToken was modified, but its similar method, _nextToken2 was not modified.
Isn't the same modification needed?

[cowtowncoder]

Possibly; I'd need to take a closer look.

But what would be really useful would be a test case to show that it is needed, and problem this would fix.
Not sure how easy that would be create; it's just that the whole handling is quite... delicate. So there is a possibility of handling changing in unintended way as testing is unfortunately not extensive for filtering.

[cowtowncoder]

Ended up making this change manually, as part of fix for #700. I think it is legit, although not sure how to reproduce specific problem.
Thank you @T45K for contributing it!