What's the best framework (sort of jquery, extjs, etc like) to use if I'd like to intensively use all the freshest technologies of the HTML5 stack provided by modern browsers (Firefox 7, Safari 5, Chrome 14) and have absolutely no need to support any legacy browsers (incl. no need in IE support at all and no need in Firefox or Chrome prior to the latest stable releases)? I'd like to get all the newest available goodness without having (even abstracted by a library layer) a line of code meant just fore legacy compatibility or keeping any legacy-induced things in mind.
To soften the filter, taking very humble hope of such an ideally fresh framework to exist, the least (the maximum level of legacy support) I'd like to agree is not supporting IE versions older than IE8, or better just not supporting IE at all.