[JS] Remove non-functional IGNORE_FIR directive in js box tests

js/js.translator/testData/box/crossModuleRef/inheritance.kt

@@ -1,4 +1,3 @@
-// IGNORE_FIR
 // EXPECTED_REACHABLE_NODES: 1292
 // MODULE: lib
 // FILE: lib.kt
@@ -24,4 +23,4 @@ fun box(): String {
     val result = B().bar()
     if (result != 24) return "fail: $result"
     return "OK"
-}
+}