Add weakmap-shim @1.1.0
Add weakmap-shim @1.1.0

Required by the todomvc example

eightyeight/mercury,martintietz/mercury,tommymessbauer/mercury,eriser/mercury,staltz/mercury,Raynos/mercury,mpal9000/mercury,jxson/mercury,beni55/mercury,vlad-x/mercury,staltz/mercury