[presubmit] Enable readability/namespace linter checking.

src/json-parser.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_JSON_PARSER_H_
 #define V8_JSON_PARSER_H_
 
 #include "src/char-predicates.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
@@ skipping 827 matching lines @@
       factory()->NewRawOneByteString(length, pretenure_).ToHandleChecked();
   uint8_t* dest = SeqOneByteString::cast(*result)->GetChars();
   String::WriteToFlat(*source_, dest, beg_pos, position_);
 
   DCHECK_EQ('"', c0_);
   // Advance past the last '"'.
   AdvanceSkipWhitespace();
   return result;
 }
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_JSON_PARSER_H_