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

js/js.translator/testData/box/multiModule/clashedInternalDeclarations.kt

@@ -1,4 +1,3 @@
-// IGNORE_FIR
 // EXPECTED_REACHABLE_NODES: 1284
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
@@ -41,4 +40,4 @@ import foo.*
 
 fun box(): String {
     return o() + k()
-}
+}