Error messages about "var with open / custom setter initialization" changed accordingly with the new backing field syntax

compiler/testData/codegen/box/objects/kt535.kt

@@ -0,0 +1,21 @@
+class Identifier<T>(t : T?, myHasDollar : Boolean) {
+    private val myT : T?
+
+    public fun getName() : T? { return myT }
+
+    companion object {
+        open public fun <T> init(name : T?) : Identifier<T> {
+            val __ = Identifier<T>(name, false)
+            return __
+        }
+    }
+    init {
+        myT = t
+    }
+}
+
+fun box() : String {
+    var i3 : Identifier<String?>? = Identifier.init<String?>("name")
+    System.out?.println(i3?.getName())
+    return "OK"
+}