[modules] Do basic linking.

test/mjsunit/modules-imports4.js

Index: test/mjsunit/modules-imports4.js
diff --git a/test/mjsunit/modules-imports4.js b/test/mjsunit/modules-imports4.js
new file mode 100644
index 0000000000000000000000000000000000000000..4d734878aa08bcb07c924b06d933a3889cbadc97
--- /dev/null
+++ b/test/mjsunit/modules-imports4.js
@@ -0,0 +1,31 @@
+// 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
+
+import {b, c} from "modules-skip-2.js";
+import {a, set_a} from "modules-skip-1.js";
+import x from "modules-skip-2.js";
+
+assertEquals(42, x);
+
+assertEquals(1, a);
+assertEquals(1, b);
+assertEquals(1, c);
+
+set_a(2);
+assertEquals(2, a);
+assertEquals(2, b);
+assertEquals(2, c);
+
+assertThrows(() => a = 3, TypeError);
+assertThrows(() => b = 3, TypeError);
+assertThrows(() => c = 3, TypeError);
+
+assertEquals(2, a);
+assertEquals(2, b);
+assertEquals(2, c);
+
+assertThrows(() => x = 43, TypeError);
+assertEquals(42, x);