[JS IR BE] Fix private members lowering

- visit over file instead of class

js/js.translator/testData/box/propertyAccess/privateClassesWithPrivateMembers.kt

@@ -0,0 +1,14 @@
+// EXPECTED_REACHABLE_NODES: 1305
+
+private class A {
+    private val f = "OK"
+    inline fun ii() = f
+}
+
+
+private class B {
+    private val a = A()
+    fun foo() = a.ii()
+}
+
+fun box() = B().foo()