[modules] Basic support of exports

test/mjsunit/modules-exports2.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// MODULE
+
+export function foo() { return 42 }
+assertEquals(42, foo());
+foo = 1;
+assertEquals(1, foo);
+
+let gaga = 43;
+export {gaga as gugu};
+assertEquals(43, gaga);
+
+export default (function bar() { return 43 })
+assertThrows(() => bar(), ReferenceError);
+assertThrows("default", SyntaxError);
+assertThrows("*default*", SyntaxError);
+
+
+var bla = 44;
+var blu = 45;
+export {bla};
+export {bla as blu};
+export {bla as bli};
+assertEquals(44, bla);
+assertEquals(45, blu);
+bla = 46;
+assertEquals(46, bla);
+assertEquals(45, blu);