[JS IR] Support per-file mode and ES modules

js/js.translator/testData/box/esModules/native/inheritanceInNativeClass.kt

@@ -0,0 +1,59 @@
+// DONT_TARGET_EXACT_BACKEND: JS
+// ES_MODULES
+
+// FILE: main.kt
+
+@JsExport
+open class A {
+    @JsName("foo")
+    open protected fun foo(n: Int) = 23
+
+    @JsName("bar")
+    fun bar(n: Int) = foo(n) + 100
+}
+
+@JsExport
+open class B {
+    @JsName("foo")
+    protected fun foo(n: Int) = 42
+
+    @JsName("bar")
+    open fun bar(n: Int) = 142
+}
+
+// FILE: entry.mjs
+// ENTRY_ES_MODULE
+
+import { A, B } from "./JS_TESTS/index.js";
+
+function createA() {
+    function ADerived() {
+    }
+    ADerived.prototype = Object.create(A.prototype);
+    ADerived.prototype.foo = function(n) {
+        return 24;
+    };
+    return new ADerived();
+}
+
+function createB() {
+    function BDerived() {
+    }
+    BDerived.prototype = Object.create(B.prototype);
+    BDerived.prototype.bar = function(n) {
+        return this.foo(n);
+    };
+    return new BDerived();
+}
+
+function box() {
+    let a = createA();
+    if (a.bar(0) != 124) return "fail1";
+
+    let b = createB();
+    if (b.bar(0) != 42) return "fail2";
+
+    return "OK";
+}
+
+console.assert(box() == "OK");