[presubmit] Enable readability/namespace linter checking.

test/cctest/gay-shortest.h

Index: test/cctest/gay-shortest.h
diff --git a/test/cctest/gay-shortest.h b/test/cctest/gay-shortest.h
index 4efe76ba0b21cf66cd435e53da1e7157312d0624..b76476ea5248a90aa337c5880f6aeeb7e8334369 100644
--- a/test/cctest/gay-shortest.h
+++ b/test/cctest/gay-shortest.h
@@ -41,6 +41,7 @@ struct PrecomputedShortest {
 
 Vector<const PrecomputedShortest> PrecomputedShortestRepresentations();
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // GAY_SHORTEST_H_