Add --enable-wasm to wasm tests.

test/mjsunit/wasm/verify-function-simple.js

 // Copyright 2015 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
+
 load("test/mjsunit/wasm/wasm-constants.js");
 
 try {
   var data = bytes(
       0,       kAstStmt,  // signature
       3,       0,         // local int32 count
       4,       0,         // local int64 count
       5,       0,         // local float32 count
       6,       0,         // local float64 count
       kExprNop            // body
@@ skipping 18 matching lines @@
   );
 
   WASM.verifyFunction(data);
   print("not ok");
 } catch (e) {
   print("ok: " + e);
   threw = true;
 }
 
 assertTrue(threw);