Generate singleton references as GET_OBJECT in nested classes

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

@@ -0,0 +1,57 @@
+object Z {
+    var counter = 0
+    fun foo() {}
+
+    fun bar() {
+        counter = 1
+        foo()
+        Z.counter = 1
+        Z.foo()
+    }
+
+    class Nested {
+        init {
+            counter = 1
+            foo()
+            Z.counter = 1
+            Z.foo()
+        }
+
+        fun test() {
+            counter = 1
+            foo()
+            Z.counter = 1
+            Z.foo()
+        }
+    }
+
+    val aLambda = {
+        counter = 1
+        foo()
+        Z.counter = 1
+        Z.foo()
+    }
+
+    val anObject = object {
+        init {
+            counter = 1
+            foo()
+            Z.counter = 1
+            Z.foo()
+        }
+
+        fun test() {
+            counter = 1
+            foo()
+            Z.counter = 1
+            Z.foo()
+        }
+    }
+}
+
+fun Z.test() {
+    counter = 1
+    foo()
+    Z.counter = 1
+    Z.foo()
+}