.unwrap() does not restore prototype methods correcty

[overlookmotel]

If you wrap an object method which is inherited from the object's prototype, and then .unwrap(), it doesn't remove the object's own method. So the object is left in a different state from how it began.

function C() {}
C.prototype.myMethod = function() { return 'A'; };

var c = new C();

console.log( Object.keys(c).length ); // outputs 0

shimmer.wrap(c, 'myMethod', function(_myMethod) {
    return function() {
       return _myMethod() + 'X';
    };
});

shimmer.unwrap(c, 'myMethod');

console.log( Object.keys(c).length ); // outputs 1

c.myMethod has been restored to its original value, but it's now present on the object, rather than inherited from the prototype.

Now, if you make a change to the prototype, it's not reflected in the behavior of the object method.

C.prototype.myMethod = function() { return 'B'; };
console.log( c.myMethod() ); // still outputs 'A'

The docs for .unwrap() say it is "for restoring the function back the way it was before you started". This is a bit ambiguous, but if you read this as "restoring everything back the way it was" then the current behavior is incorrect.

Perhaps this is a rather small point, but it bit me on something, so I thought I'd raise it.

[overlookmotel]

Any interest in a PR to fix this?

[overlookmotel]

Now that this module is a bit active again, would you accept a PR for this?