Bug report in xaringan chrome print in ratio 16:9 option

Hi All,

I found that ratio: "16:9" option generates the issue that the print pdf doesn't capture the plots.

(Slide in chrome)

(PDF print out)

Reproducible Rmd:

---
title: "Presentation Ninja"
subtitle: "test; xaringanthemer"  
author: 
  - "Yihui Xie"
date: '`r Sys.Date()`'
output:
  xaringan::moon_reader:
    lib_dir: libs
    css: xaringan-themer.css
    nature:
      highlightStyle: github
      highlightLines: true
      countIncrementalSlides: false
      ratio: "16:9"
---

```{r setup, include=FALSE}
options(htmltools.dir.version = FALSE)
```

# Easy Example

.pull-left[
Random contents 

]
.pull-right[
```{r, echo=FALSE}
x <- y <- 1:5
plot(x, y)
```

]