[wasm] Support wasm module structured cloning.

third_party/WebKit/LayoutTests/http/tests/wasm/wasm_serialization_worker.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.
+
+onmessage = function(e) {
+    var compiled_module = e.data;
+    var instance = new WebAssembly.Instance(compiled_module);
+    if (instance === undefined) {
+        postMessage("error!");
+        return;
+    }
+    var entrypoint = instance.exports["increment"];
+
+    if (typeof entrypoint !== "function") {
+        postMessage("error!");
+        return;
+    }
+
+    var ret = entrypoint(42);
+    postMessage(ret);
+}