Design Doc: LeapTiering (i.e., a shared code pointer for all related JsFunctions)

[Olivier Flückiger]

Hi all,

this discussion already made the rounds in some places but here comes a more fleshed out proposal finally. Roughly, the plan is to move the code pointer from JSFunctions to feedback cells, to be able to have all function objects of the same source function always point to the same, most up-to-date code object.

ptal at 

https://docs.google.com/document/d/1Rf_Y7vLOYDCAVcpdJnSkwWcJeHj1K3CR2laF_oPbCZc/edit?usp=sharing

*oli