8048079: Persistent code store is broken after optimistic types merge
Reviewed-by: sundar, jlaskey, attila
x instanceof f: true
x instanceof b: true
y instanceof f: true
y instanceof b: true
Changing prototype
x instanceof f: false
x instanceof b: false
y instanceof f: false
y instanceof b: false
Bound function prototype
f.hasOwnProperty('prototype'): true
b.hasOwnProperty('prototype'): false