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

test/mjsunit/wasm/no-wasm-by-default.js

Index: test/mjsunit/wasm/no-wasm-by-default.js
diff --git a/test/mjsunit/wasm/no-wasm-by-default.js b/test/mjsunit/wasm/no-wasm-by-default.js
new file mode 100644
index 0000000000000000000000000000000000000000..2f9622e2c4389047528e3bc13ef275619886bf7b
--- /dev/null
+++ b/test/mjsunit/wasm/no-wasm-by-default.js
@@ -0,0 +1,6 @@
+// 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; });