Not possible to store PerformanceAnalytics chart in an R object

### Description

I am not able to store PerformanceAnalytics chart in an R object like ggplot.

### Minimal, reproducible example

```r
library(PerformanceAnalytics)
data(managers)
x <- chart.Correlation(managers[,1:8], histogram=TRUE, pch="+")
x
```


