A few additions:

KHTML was originally forked from QHtml (part of Qt) I believe (or they shared the same origin?).

Webkit later became a Qt component, the circle of life.

I would argue chromes biggest innovation was the UI, putting the address bar as part of the tab where it belongs (cue holy war) and better tabbing in general.

Mozilla was also the first to integrate the search and address fields, which they unfortunately stripped out of firefox (and many people think chrome introduced it).