The JS rendering engine is the most proprietary and slowest of all of the browsers. I work with automation software and it is, by far, the most particular and problematic (over anything built on WebKit like Chrome and Safari or Firefox).
"The box said requires windows xp or better, so I installed Linux"
Google search comes ahead with things like internet explorer opens many tabs -- most of the responses say 'malware'
Erm...you do know that Firefox is built on the Gecko rendering with it's own JS engine, currently called IonMonkey
in FF18. Chrome has Google's V8
JS engine, and Safari has the Nitro
And proprietary is a relative term. Especially with Google's V8 engine, which is at the core of NodeJS. That and all of the Mozilla engines are F/OSS and can be re-used, modified, updated, etc with various minimal restrictions elsewhere, or even if your own browser. Hardly proprietary.