[presubmit] Enable readability/namespace linter checking.

src/v8memory.h

 // Copyright 2011 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.
 
 #ifndef V8_MEMORY_H_
 #define V8_MEMORY_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 48 matching lines @@
 
   static Object*& Object_at(Address addr)  {
     return *reinterpret_cast<Object**>(addr);
   }
 
   static Handle<Object>& Object_Handle_at(Address addr)  {
     return *reinterpret_cast<Handle<Object>*>(addr);
   }
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_MEMORY_H_