Forbid callable references to members and extensions with empty LHS

This syntax is reserved to be likely used in the future as a shorthand for
"this::foo" where the resulting expression doesn't take the receiver as a
parameter but has "this" already bound to it

js/js.translator/testData/callableReference/function/cases/classMemberFromClass.kt

@@ -4,7 +4,7 @@ package foo
 class A {
     fun bar(k: Int) = k
 
-    fun result() = (::bar)(this, 111)
+    fun result() = (A::bar)(this, 111)
 }
 
 fun box(): String {