[presubmit] Enable readability/namespace linter checking.

src/x64/frames-x64.h

 // Copyright 2012 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_X64_FRAMES_X64_H_
 #define V8_X64_FRAMES_X64_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 53 matching lines @@
   static const int kLocal0Offset = StandardFrameConstants::kExpressionsOffset;
   static const int kLastParameterOffset = kFPOnStackSize + kPCOnStackSize;
   static const int kFunctionOffset = StandardFrameConstants::kMarkerOffset;
 
   // Caller SP-relative.
   static const int kParam0Offset   = -2 * kPointerSize;
   static const int kReceiverOffset = -1 * kPointerSize;
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_X64_FRAMES_X64_H_