1) A browser's full JS implementation is pretty closely coupled with its rendering engine. Both Safari and Chrome use WebKit as a rendering engine.. 2) In the

1) A browser's full JS implementation is pretty closely coupled with its rendering engine. Both Safari and Chrome use WebKit as a rendering engine.. 2) In the real world open source software is about scratching your own itch, and has absolutely nothing to do with "what's best for users". In this world, WebKit is open sourced by Apple and isn't some random user's side project that gets one patch a month. This means that decisions aren't made lightly, without second thought. Including the decision that was made to merge back with KHTML and Google's (slow) progress to move back to using WebKit trunk instead of their own fork.