Fix Bug 941016, implement prebrowsing stage 1 to improve frontend performance

@AdrianGaudebert r? To be honest, this is going to be next to impossible to test anywhere other than on stage and production so... Not sure how you should test it, I guess, as long as nothing breaks ;) On stage and production we should take a measurement of the perceived load time of the page pre implementation and post implementation, with a clean browser cache in both instances navigating to the landing page and then to top crashers for example.

If, we find that this gives a measurable performance bump, I can look into implementing more aggressive 'prebrowsing' in instances where there is a big potential benefit.