Fixed incorrect returned by infector value. If Constructor returned object it shouldn't be 'this'

Hi, it's nice product! But I found some glitch.
When Contructor returns object, then it's must be new `this` value.
Example: 
```javascript
function Test() {
    return {
        doTest: 'test value'
    };
}
var test = new Test();
console.log(test);
//Should be: Object {doTest: "test value"} 
//Now: Object {}
```
But now it will be empty object, i.e. `this` of object.