Add more missing closing namespace comments.

third_party/WebKit/Source/core/testing/UnionTypesTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/testing/UnionTypesTest.h"
 
 #include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
@@ skipping 141 matching lines @@
     StringBuilder builder;
     builder.append("sequence: [");
     for (const String& item : sequence) {
         ASSERT(!item.isNull());
         builder.append(item);
         builder.append(", ");
     }
     return builder.substring(0, builder.length() - 2) + "]";
 }
 
-}
+} // namespace blink