[modules] Initialize requested_modules before recursing in Module::Instantiate

Also fix recursive call to avoid going back through the API.

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

Review-Url: https://codereview.chromium.org/2366063002
Cr-Commit-Position: refs/heads/master@{#39696}

src/api.cc

@@ -1976,10 +1976,11 @@ static bool InstantiateModule(Local<Module> v8_module,
       isolate->ThrowIllegalOperation();
       return false;
     }
-    if (!requested_module->Instantiate(v8_context, callback, callback_data)) {
+    module->requested_modules()->set(i, *Utils::OpenHandle(*requested_module));
+    if (!InstantiateModule(requested_module, v8_context, callback,
+                           callback_data)) {
       return false;
     }
-    module->requested_modules()->set(i, *Utils::OpenHandle(*requested_module));
   }
 
   // Resolve imports.

test/mjsunit/modules-circular-valid.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 {a as b} from "modules-skip-circular-valid.js";

test/mjsunit/modules-skip-circular-valid.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 a = {key: 'value'};
+import {b} from "modules-circular-valid.js";
+assertSame(a, b);
+assertEquals('value', a.key);