8047959: bindings created for declarations in eval code are not mutable
Reviewed-by: jlaskey, attila
delete x? false
typeof x = number
delete f? true
typeof f = undefined
delete foo? false
typeof foo = number
delete func? false
typeof func = function
delete foo? false
typeof foo? number
foo = 33
x in function = local
delete x? = true
x after delete = global
x = global