KT-2752: add basic tests for JsName

js/js.translator/testData/box/jsName/overriddenMethod.kt

@@ -0,0 +1,20 @@
+package foo
+
+open class A {
+    @JsName("js_f") open fun f(x: Int) = "A.f($x)"
+}
+
+class B : A() {
+    override fun f(x: Int) = "B.f($x)"
+}
+
+fun test() = js("""
+var module = Kotlin.modules.JS_TESTS.foo;
+return new (module.A)().js_f(23) + ";" + new (module.B)().js_f(42);
+""")
+
+fun box(): String {
+    val result = test()
+    assertEquals("A.f(23);B.f(42)", result);
+    return "OK"
+}