Just to be clear the proposal I'm making would be that all these libs are pre-included in the browser. This wouldn't just be a special non-deletable cache where

Just to be clear the proposal I'm making would be that all these libs are pre-included in the browser. This wouldn't just be a special non-deletable cache where the libraries are pulled lazily on first use. It'd be an entirely separate concept from the current browser cache of JS files, in fact. Potentially 'cache' is a bit of a misleading term here. There's probably a bit of a question of what to do when new versions and/or new libs are included in the index (probably download new ones periodically or upon a notification) where there could feasibly be some lag time where that lib/version isn't available yet. But that'd be an edge case situation.