[modules] Add tests for empty imports.

R=adamk@chromium.org
BUG=v8:1569

Review-Url: https://codereview.chromium.org/2369133002
Cr-Commit-Position: refs/heads/master@{#39739}

test/mjsunit/modules-empty-import1.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
+
+import "modules-skip-empty-import.js";
+import {counter} from "modules-skip-empty-import-aux.js";
+assertEquals(1, counter);

test/mjsunit/modules-empty-import2.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
+
+import {} from "modules-skip-empty-import.js";
+import {counter} from "modules-skip-empty-import-aux.js";
+assertEquals(1, counter);

test/mjsunit/modules-empty-import3.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 {} from "modules-skip-empty-import.js";
+import {counter} from "modules-skip-empty-import-aux.js";
+assertEquals(1, counter);

test/mjsunit/modules-empty-import4.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
+
+import "modules-skip-empty-import.js";
+import {} from "modules-skip-empty-import.js";
+export {} from "modules-skip-empty-import.js";
+import {counter} from "modules-skip-empty-import-aux.js";
+assertEquals(1, counter);

test/mjsunit/modules-skip-empty-import-aux.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.
+
+export let counter = 0;
+export function incr() { counter++ };

test/mjsunit/modules-skip-empty-import.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.
+
+import {incr} from "modules-skip-empty-import-aux.js";
+incr();