If we hit an EOF token, and the character before the EOF is a newline,
we should make EOF token start at the previous newline. That way any
errors reported will occur on that line.
For example "foo(\n" should report an error on line 1 even though the
EOF technically occurs on line 2.
[Bug #20918]
https://bugs.ruby-lang.org/issues/2091860bc43de8e
