[wasm] Enable WASM by default (--expose-wasm=true).

test/mjsunit/wasm/wasm-default.js

Index: test/mjsunit/wasm/wasm-default.js
diff --git a/test/mjsunit/wasm/wasm-default.js b/test/mjsunit/wasm/wasm-default.js
new file mode 100644
index 0000000000000000000000000000000000000000..8d34ebbe1dceceb146cc5f993fccc67c26a82ab1
--- /dev/null
+++ b/test/mjsunit/wasm/wasm-default.js
@@ -0,0 +1,19 @@
+// 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.
+
+function GetWebAssembly() {
+  return WebAssembly;
+}
+
+let WASM_ON_BY_DEFAULT = true;
+
+if (WASM_ON_BY_DEFAULT) {
+  try {
+    assertFalse(undefined === GetWebAssembly());
+  } catch (e) {
+    assertTrue(false);
+  }
+} else {
+  assertThrows(GetWebAssembly);
+}