Test new_instance_should_point_to_prototype is not checked correctly

[54k1]

Describe the bug
The test just checks if the prototype of the instance is an object using the is_object method.

Consider the following js snippet (similar to the example in the test):

function Foo () {}
var bar = new Foo();

The test currently asserts typeof bar.__proto__ === "object"
Rather it should assert bar.__proto__ === Foo.prototype.

I guess the point of the test was to just check if bar.__proto__ was an object. But it's good to go one step further to assert that the prototype is correctly assigned to be Foo.prototype