Put 'thisReceiver' declaration in class

Interfaces also have 'thisReceiver'

compiler/testData/ir/irText/expressions/thisOfGenericOuterClass.kt

@@ -0,0 +1,8 @@
+class Outer<T>(val x: T) {
+    open inner class Inner(val y: Int)
+}
+
+fun Outer<Int>.test() =
+        object : Outer<Int>.Inner(42) {
+            val xx = x + y
+        }