Adds `Renderer::clean`, and fixes crash in `PerformanceTest/Node

children Test`.

cocos/2d/renderer/CCRenderer.cpp

@@ -359,6 +359,12 @@ void Renderer::render()
         }
     }
 
+    clean();
+}
+
+void Renderer::clean()
+{
+    // Clear render group
     for (size_t j = 0 ; j < _renderGroups.size(); j++)
     {
         //commands are owned by nodes
@@ -369,11 +375,17 @@ void Renderer::render()
         _renderGroups[j].clear();
     }
 
-    //Clear the stack incase gl view hasn't been initialized yet
+    // Clear batch quad commands
+    _batchedQuadCommands.clear();
+    _numQuads = 0;
+
+    // Clear the stack incase gl view hasn't been initialized yet
     while(!_renderStack.empty())
     {
         _renderStack.pop();
     }
+
+    // Reset render stack
     RenderStackElement element = {DEFAULT_RENDER_QUEUE, 0};
     _renderStack.push(element);
     _lastMaterialID = 0;

cocos/2d/renderer/CCRenderer.h

@@ -98,6 +98,9 @@ public:
     /** Renders into the GLView all the queued `RenderCommand` objects */
     void render();
 
+    /** Cleans all `RenderCommand`s in the queue */
+    void clean();
+
     /* returns the number of drawn batches in the last frame */
     ssize_t getDrawnBatches() const { return _drawnBatches; }
     /* RenderCommands (except) QuadCommand should update this value */

tests/cpp-tests/Classes/PerformanceTest/PerformanceNodeChildrenTest.cpp

@@ -947,6 +947,10 @@ void VisitSceneGraph::update(float dt)
     CC_PROFILER_START( this->profilerName() );
     this->visit();
     CC_PROFILER_STOP( this->profilerName() );
+
+    // Call `Renderer::clean` to prevent crash if current scene is destroyed.
+    // The render commands associated with current scene should be cleaned.
+    Director::getInstance()->getRenderer()->clean();
 }
 
 std::string VisitSceneGraph::title() const