This seams like a very important performance feature that must be included in the vm and dartium. Could this also applies to html imports? I have followed the posts from ilya grigorik about 1 second load times for web pages and js deferring and other code loading is fundamental so i dont see any reason not to do it on the vm. I hope it comes soon to the vm also
As Kasper said in comment 3, so far this has been discussed a deployment feature which you will get with dart2dart. The VMs involvement in supporting this ends with giving the dart2dart generated code access to loading sources lazily through a library call. This library API still needs to be specified though.