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

js/js.translator/testData/box/inlineMultiModule/importStdLib.kt

@@ -1,4 +1,3 @@
-// IGNORE_FIR
 // EXPECTED_REACHABLE_NODES: 1376
 // MODULE: lib
 // FILE: lib.kt
@@ -25,4 +24,4 @@ fun bar(i: Int):Int {
 fun box():String {
     if (foo(10, 20.0) + bar(-10) != 0) return "FAIL"
     return "OK"
-}
+}