Fix for a bug that caused invalid code generated for calling extension from another extension.

js/js.translator/testFiles/extensionFunction/cases/superClassMemberInExtension.kt

@@ -0,0 +1,14 @@
+package foo
+
+open class A() {
+    open fun c() = 2
+}
+
+class B(): A() {
+}
+
+fun B.d() = c() + 3
+
+fun box() : Boolean {
+    return B().d() == 5
+}