src: fix readability/inheritance cpplint warnings

PR-URL: #7462
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

Author: bnoordhuis

src/async-wrap.cc

@@ -39,11 +39,11 @@ class RetainedAsyncInfo: public RetainedObjectInfo {
  public:
   explicit RetainedAsyncInfo(uint16_t class_id, AsyncWrap* wrap);
 
-  virtual void Dispose() override;
-  virtual bool IsEquivalent(RetainedObjectInfo* other) override;
-  virtual intptr_t GetHash() override;
-  virtual const char* GetLabel() override;
-  virtual intptr_t GetSizeInBytes() override;
+  void Dispose() override;
+  bool IsEquivalent(RetainedObjectInfo* other) override;
+  intptr_t GetHash() override;
+  const char* GetLabel() override;
+  intptr_t GetSizeInBytes() override;
 
  private:
   const char* label_;

src/cares_wrap.cc

@@ -256,7 +256,7 @@ class QueryWrap : public AsyncWrap {
       req_wrap_obj->Set(env->domain_string(), env->domain_array()->Get(0));
   }
 
-  virtual ~QueryWrap() override {
+  ~QueryWrap() override {
     CHECK_EQ(false, persistent().IsEmpty());
     persistent().Reset();
   }

src/fs_event_wrap.cc

@@ -34,7 +34,7 @@ class FSEventWrap: public HandleWrap {
 
  private:
   FSEventWrap(Environment* env, Local<Object> object);
-  virtual ~FSEventWrap() override;
+  ~FSEventWrap() override;
 
   static void OnEvent(uv_fs_event_t* handle, const char* filename, int events,
     int status);

src/handle_wrap.h

@@ -48,7 +48,7 @@ class HandleWrap : public AsyncWrap {
              uv_handle_t* handle,
              AsyncWrap::ProviderType provider,
              AsyncWrap* parent = nullptr);
-  virtual ~HandleWrap() override;
+  ~HandleWrap() override;
 
  private:
   friend class Environment;

src/node_stat_watcher.h

@@ -11,7 +11,7 @@ namespace node {
 
 class StatWatcher : public AsyncWrap {
  public:
-  virtual ~StatWatcher() override;
+  ~StatWatcher() override;
 
   static void Initialize(Environment* env, v8::Local<v8::Object> target);