add test files

js/js.translator/testFiles/operatorOverloading/cases/postfixOnProperty.kt

@@ -0,0 +1,18 @@
+package foo
+
+var a = MyInt()
+
+class MyInt() {
+  var b = 0
+
+    fun inc() : MyInt {
+      b = b + 1;
+      return this;
+    }
+}
+
+
+fun box() : Boolean {
+    val d = a++;
+    return (a.b == 1) && (d.b == 1);
+}