What did Imogen Herondale whisper to Jace Wayland when she died?

*SPOILER ALERT (if you havent read up to City of Glass)

She says, "Your father would be proud of you"-- City of Glass, p513 (hardcover)

*SPOILER ALERT

What she's referring to is when she realizes Jace is actually the son of Stephen Herondale-- and her grandson.