[presubmit] Enable readability/namespace linter checking.

test/cctest/test-heap-profiler.cc

Index: test/cctest/test-heap-profiler.cc
diff --git a/test/cctest/test-heap-profiler.cc b/test/cctest/test-heap-profiler.cc
index 55e553868b5f5534c9f2a018d6218dc810e8f00e..909aba0d74216deb77fa732b9a8c37f4a915db53 100644
--- a/test/cctest/test-heap-profiler.cc
+++ b/test/cctest/test-heap-profiler.cc
@@ -1351,7 +1351,8 @@ class TestActivityControl : public v8::ActivityControl {
   int total_;
   int abort_count_;
 };
-}
+
+}  // namespace
 
 
 TEST(TakeHeapSnapshotAborting) {
@@ -1444,7 +1445,8 @@ class TestRetainedObjectInfo : public v8::RetainedObjectInfo {
 
 
 i::List<TestRetainedObjectInfo*> TestRetainedObjectInfo::instances;
-}
+
+}  // namespace
 
 
 static const v8::HeapGraphNode* GetNode(const v8::HeapGraphNode* parent,