Boolean DeleteBinding(N:String)
Attempts to delete the Binding N. Action is ignored if N does not exist in this Declarative Environment Record.
In these examples, a Binding is an object {value:mixed, mutable:Boolean, deletable:Boolean, initialized:Boolean}
function DeleteBinding(N){
var envRec = this;
if (!(N in envRec)) return true; // note: if it doesnt exist, true is returned indicating a success!
if (!envRec[N].deletable) return false;
delete envRec[N];
return true;
};