[wasm] Support wasm module structured cloning.

third_party/WebKit/LayoutTests/http/tests/wasm/wasm_serialization_tests.js

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+function instantiateInWorker() {
+  // the file incrementer.wasm is copied from
+  // //v8/test/mjsunit/wasm. This is because currently we cannot
+  // reference files outside the LayoutTests folder. When wasm format
+  // changes require that file to be updated, there is a test on the
+  // v8 side (same folder), ensure-wasm-binaries-up-to-date.js, which
+  // fails and will require incrementer.wasm to be updated on that side.
+  return fetch('incrementer.wasm')
+    .then(response => {
+      if (!response.ok) throw new Error(response.statusText);
+      return response.arrayBuffer();
+    })
+    .then(data => {
+      var mod = new WebAssembly.Module(data);
+      var worker = new Worker("wasm_serialization_worker.js");
+      return new Promise((resolve, reject) => {
+        worker.postMessage(mod);
+        worker.onmessage = function(event) {
+          resolve(event.data);
+        }
+      });
+    })
+    .then(data => assert_equals(data, 43))
+    .catch(error => assert_unreached(error));
+}