[modules] Basic support of exports

test/mjsunit/modules-exports1.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 var myvar = "VAR";
+assertEquals("VAR", myvar);
+assertEquals("VAR", eval("myvar"));
+(() => assertEquals("VAR", myvar))();
+
+export let mylet = "LET";
+assertEquals("LET", mylet);
+assertEquals("LET", eval("mylet"));
+(() => assertEquals("LET", mylet))();
+
+export const myconst = "CONST";
+assertEquals("CONST", myconst);
+assertEquals("CONST", eval("myconst"));
+(() => assertEquals("CONST", myconst))();
+
+
+myvar = 1;
+assertEquals(1, myvar);
+assertEquals(1, eval("myvar"));
+(() => assertEquals(1, myvar))();
+(() => myvar = 2)();
+assertEquals(2, myvar);
+(() => assertEquals(2, myvar))();
+{
+  let f = () => assertEquals(2, myvar);
+  f();
+}
+
+mylet = 1;
+assertEquals(1, mylet);
+assertEquals(1, eval("mylet"));
+(() => assertEquals(1, mylet))();
+(() => mylet = 2)();
+assertEquals(2, mylet);
+assertEquals(2, eval("mylet"));
+(() => assertEquals(2, mylet))();
+{
+  let f = () => assertEquals(2, mylet);
+  f();
+}
+
+assertThrows(() => myconst = 1, TypeError);
+assertEquals("CONST", myconst);
+assertEquals("CONST", eval("myconst"));
+(() => assertEquals("CONST", myconst))();
+{
+  let f = () => assertEquals("CONST", myconst);
+  f();
+}