Prior to this change, the grammar showed that the asterisk in the '*/' pair
that closes a block comment was optional. This change updates the grammar
rule to require at least one asterisk to appear.
* Initial port of the C# 6 specification; all the heavy lifting had been done by @ljw1004
* Remove pdf, html versions and grammar versions until we figure out how to build them.
Drew Noakes
Carl Reinke
stakx
Sam Harwell
Neal Gafter