JS: add tests for two libraries and js-file with two modules

compiler/testData/integration/ant/js/simpleWithStdlibAndJsFilesWithTwoModulesAsLibrary/root1/foo.kt

@@ -0,0 +1,15 @@
+package foo
+
+import library.sample.*
+import kotlin.js.Date
+
+var ok = "FAIL"
+
+fun main(args: Array<String>) {
+    val x = ClassA().value
+    if (x == 100 && Date().extFun() == "Date.extFun" && ClassA().extFun() == "ClassA.extFun") {
+        ok = "OK"
+    }
+}
+
+fun box(): String = ok