When InterfaceAdapter is used, the wrong thisObj is used

[rPraml]

I had an issue when I pass a JS object to Java class and an InterfaceAdapter is constructed:

Java interface

public interface AdapterInterface {
        int m1(int i);
        int m2();
}

Corresponding impl. in javascript:

function Obj() { this.myObj = {one: 1} }
Obj.prototype.m1 = function(i) { return i + this.myObj.one } // this.myObj is undefined
Obj.prototype.m2 = function() { return 7 }

When I pass this object in my AdapterClass, I get the error: this.myObj is undefined
This PR provides a test and a possible fix

[rPraml]

thisObject is an instance of JavaAdapterInvokeTest.AdapterClass and we want to call a method on target

[gbrail]

This seems logical to me but it's a pretty fundamental thing to the Java embedding support and I'd like to see someone who works with this stuff regularly take a look before merging it.