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

js/js.translator/testData/box/esModules/jsModule/externalPackage.mjs

@@ -0,0 +1,24 @@
+export function A(x) {
+    this.x = x;
+}
+A.prototype.foo = function (y) {
+    return this.x + y;
+};
+
+function Nested() {
+    this.y = 55;
+}
+A.Nested = Nested;
+
+export var B = {
+    x: 123,
+    foo: function(y) {
+        return this.x + y;
+    }
+};
+
+export function foo(y) {
+    return 323 + y;
+}
+
+export var bar = 423;