[presubmit] Enable readability/namespace linter checking.

src/base/atomicops_internals_portable.h

Index: src/base/atomicops_internals_portable.h
diff --git a/src/base/atomicops_internals_portable.h b/src/base/atomicops_internals_portable.h
index a3a6e74c72e53bdb6c126be44b5e7622837e25a1..bb9997378624fb02afe7a1df95ad29d4ecad3ca0 100644
--- a/src/base/atomicops_internals_portable.h
+++ b/src/base/atomicops_internals_portable.h
@@ -132,7 +132,7 @@ inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
 inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
   return __sync_add_and_fetch(ptr, 0);
 }
-}
-}  // namespace v8::base
+}  // namespace base
+}  // namespace v8
 
 #endif  // V8_BASE_ATOMICOPS_INTERNALS_PORTABLE_H_