DERBY-6017: IN lists with mixed types may return wrong results

Cast the left operand to the dominant type if it isn't already of
that type. This ensures the dominant type is always used in all the
comparison operations when evaluating an IN predicate.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1448025 13f79535-47bb-0310-9956-ffa450edef68