Forbidden old invokeExtension convention.

js/js.translator/testData/expression/invoke/cases/invokeWithDispatchAndExtensionReceivers.kt

@@ -1,12 +1,9 @@
 package foo
 
 class A
-class B {
-    fun A.invoke(i: Int) = i
-}
 
 fun box(): Boolean {
     val a = A()
-    val b = B()
+    val b = fun A.(i: Int) = i
     return a.(b)(1) == 1
 }