[wasm] Dont ship by default.

R=mstarzinger@chromium.org,bradnelson@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2118733003
Cr-Commit-Position: refs/heads/master@{#37478}

src/wasm/wasm-js.cc

@@ -415,12 +415,20 @@ static Handle<JSFunction> InstallFunc(Isolate* isolate, Handle<JSObject> object,
 }
 
 void WasmJs::Install(Isolate* isolate, Handle<JSGlobalObject> global) {
+  if (!FLAG_expose_wasm && !FLAG_validate_asm) {
+    return;
+  }
+
   Factory* factory = isolate->factory();
 
   // Setup wasm function map.
   Handle<Context> context(global->native_context(), isolate);
   InstallWasmFunctionMap(isolate, context);
 
+  if (!FLAG_expose_wasm) {
+    return;
+  }
+
   // Bind the experimental WASM object.
   // TODO(rossberg, titzer): remove once it's no longer needed.
   {

test/mjsunit/wasm/no-wasm-by-default.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.
+
+// TODO(titzer): remove this test when WASM ships.
+assertThrows(function() { var g = Wasm; });