Safari is not based on "Apple's own proprietary software" it is based on "web kit" which is being developed by Apple, Nokia, Google and many othersand is Open Source. Web Kit powers server other browsers other then just Safari
Firefox is being developed by mozilla foundationand it is also open source.
I intended to say Apple products running Safari. FYI I was a Webkit user for the last two months. Where's the link suggesting Apple was using inside understanding of the Intel-Mac architecture to outpace other browsers?