code: function uploadBaseTextures(renderer, item)
  {
      if (item instanceof BaseTexture)
      {
          // if the texture already has a GL texture, then the texture has been prepared or rendered
          // before now. If the texture changed, then the changer should be calling texture.update() which
          // reuploads the texture without need for preparing it again
          if (!item._glTextures[renderer.CONTEXT_UID])
          {
              renderer.textureManager.updateTexture(item);
          }
  
          return true;
      }
  
      return false;
  }
docs: Built-in hook to upload PIXI.Texture objects to the GPU.
  
  @private
  @param {PIXI.Renderer} renderer - instance of the webgl renderer
  @param {PIXI.DisplayObject} item - Item to check
  @return {boolean} If item was uploaded.