Fix translation to JS of call to top-level fun with vararg and @JsModule

See KT-17871

js/js.translator/testData/box/jsModule/topLevelVarargFun.js

@@ -0,0 +1,5 @@
+define("bar", [], function() {
+    return function() {
+        return "(" + Array.prototype.join.call(arguments, "") + ")";
+    };
+});

js/js.translator/testData/box/jsModule/topLevelVarargFun.kt

@@ -0,0 +1,15 @@
+// EXPECTED_REACHABLE_NODES: 490
+// MODULE_KIND: AMD
+@JsModule("bar")
+external fun foo(vararg arg: String): String
+
+fun box(): String {
+    val x = arrayOf("a", "b")
+    var r = foo(*x)
+    if (r != "(ab)") return "fail1: $r"
+
+    r = foo("c", "d")
+    if (r != "(cd)") return "fail2: $r"
+
+    return "OK"
+}