I modified BaseTokenStreamTestCase to assert that the start/end
offsets match for graph (posLen > 1) tokens, and this caught a bug in
Kuromoji when the decompounding of a compound token has a punctuation
token that's dropped.
In this case we should leave hole(s) so that the graph is intact, ie,
the graph should look the same as if the punctuation tokens were not
initially removed, but then a StopFilter had removed them.
This also affects tokens that have no compound over them, ie we fail
to leave a hole today when we remove the punctuation tokens.
I'm not sure this is serious enough to warrant fixing in 3.6 at the