Correct the false comments and delete dead code

table.go

@@ -538,16 +538,6 @@ func (t *table) descendant(name string) *table {
 // parentRow is the row of t's parent that row r links to.
 func (t *table) parentRow(r int) int { return t.parentT.byKey[t.cell(r, t.parentIndex)] }
 
-// descends reports whether a is an ancestor of t.
-func (t *table) descends(a *table) bool {
-	for p := t.parentT; p != nil; p = p.parentT {
-		if p == a {
-			return true
-		}
-	}
-	return false
-}
-
 // under reports whether row r of t sits inside row pr of ancestor a.
 func (t *table) under(r int, a *table, pr int) bool {
 	for c, row := t, r; c.parentT != nil; c, row = c.parentT, c.parentRow(row) {