[core] Fix bugprone-virtual-near-miss errors

As reported by clang-tidy-8.

platform/node/src/node_request.cpp

@@ -60,7 +60,7 @@ void NodeRequest::HandleCallback(const Nan::FunctionCallbackInfo<v8::Value>& inf
     auto callback = std::move(request->callback);
     request->callback = {};
     if (!callback) {
-        request->unref();
+        request->unrefRequest();
         return info.GetReturnValue().SetUndefined();
     }
 
@@ -84,7 +84,7 @@ void NodeRequest::HandleCallback(const Nan::FunctionCallbackInfo<v8::Value>& inf
             *Nan::Utf8String(info[0])
         );
     } else if (info.Length() < 2 || !info[1]->IsObject()) {
-        request->unref();
+        request->unrefRequest();
         return Nan::ThrowTypeError("Second argument must be a response object");
     } else {
         auto res = Nan::To<v8::Object>(info[1]).ToLocalChecked();
@@ -118,7 +118,7 @@ void NodeRequest::HandleCallback(const Nan::FunctionCallbackInfo<v8::Value>& inf
                     node::Buffer::Length(data)
                 );
             } else {
-                request->unref();
+                request->unrefRequest();
                 return Nan::ThrowTypeError("Response data must be a Buffer");
             }
         }
@@ -126,15 +126,15 @@ void NodeRequest::HandleCallback(const Nan::FunctionCallbackInfo<v8::Value>& inf
 
     // Send the response object to the NodeFileSource object
     callback(response);
-    request->unref();
+    request->unrefRequest();
     info.GetReturnValue().SetUndefined();
 }
 
-void NodeRequest::unref() {
-  Nan::HandleScope scope;
-  delete asyncResource;
-  asyncResource = nullptr;
-  Unref();
+void NodeRequest::unrefRequest() {
+    Nan::HandleScope scope;
+    delete asyncResource;
+    asyncResource = nullptr;
+    Unref();
 }
 
 NodeAsyncRequest::NodeAsyncRequest() : request(nullptr) {}

platform/node/src/node_request.hpp

@@ -34,7 +34,7 @@ public:
     static void New(const Nan::FunctionCallbackInfo<v8::Value>&);
     static void HandleCallback(const Nan::FunctionCallbackInfo<v8::Value>&);
 
-    void unref();
+    void unrefRequest();
 
     mbgl::FileSource::Callback callback;
     NodeAsyncRequest* asyncRequest;