Fix ChapterIndex#number to display correct number for PREDEF/POSTDEF
Fix ChapterIndex#number to display correct number for PREDEF/POSTDEF

takahashim/review,krororo/review,kmuto/review,kuad9/review_study,murashitas/review,masawada/review,murashitas/review,orangain/review,orangain/review,suzuki/review,krororo/review,kuad9/review_study,masawada/review,kmuto/review,takahashim/review,krororo/review,suzuki/review,kmuto/review