[presubmit] Enable readability/namespace linter checking.

src/mips64/code-stubs-mips64.h

Index: src/mips64/code-stubs-mips64.h
diff --git a/src/mips64/code-stubs-mips64.h b/src/mips64/code-stubs-mips64.h
index c54a3d07c50667e96d0e4bd484f550b6b39cfeb3..2e18f59915aa183dc192b8e17d5b67ed60b67a2d 100644
--- a/src/mips64/code-stubs-mips64.h
+++ b/src/mips64/code-stubs-mips64.h
@@ -344,6 +344,7 @@ class NameDictionaryLookupStub: public PlatformCodeStub {
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_MIPS_CODE_STUBS_MIPS64_H_