[wasm] binary and test for hosts' integration tests

Ensure wasm binaries intended to be used in hosts of v8, such as
chromium, are up to date.

See https://codereview.chromium.org/2255673003/

BUG=v8:5072

Review-Url: https://codereview.chromium.org/2259693002
Cr-Commit-Position: refs/heads/master@{#38694}

test/mjsunit/wasm/ensure-wasm-binaries-up-to-date.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.
+
+// Flags: --expose-wasm
+
+// Ensure checked in wasm binaries used by integration tests from v8 hosts
+// (such as chromium) are up to date.
+
+load('test/mjsunit/mjsunit.js');
+
+(function ensure_incrementer() {
+  var buff = readbuffer("test/mjsunit/wasm/incrementer.wasm");
+  var mod = new WebAssembly.Module(buff);
+  var inst = new WebAssembly.Instance(mod);
+  var inc = inst.exports.increment;
+  assertEquals(3, inc(2));
+}())