MenuItem right icons are not styleable if desktop=false

[birnam]

https://github.com/callemall/material-ui/blob/master/src/menus/menu-item.jsx#L168-L172

if (rightIcon) {
  const mergedRightIconStyles = desktop ?
    this.mergeStyles(styles.rightIconDesktop, rightIcon.props.style) : null;
  rightIconElement = React.cloneElement(rightIcon, {style: mergedRightIconStyles});
}

In MenuItem when merging styles.rightIconDesktop with rightIcon.props.style, the merge only happens if desktop == true, otherwise it sets it to null. If desktop == false it should at least preserve the style property the developer provided for the rightIcon.

if (rightIcon) {
  const mergedRightIconStyles = desktop ?
    this.mergeStyles(styles.rightIconDesktop, rightIcon.props.style) : rightIcon.props.style;
  rightIconElement = React.cloneElement(rightIcon, {style: mergedRightIconStyles});
}

[oliviertassinari]

@birnam Thanks for finding this. Do you want to submit a PR to fix it?
I think that it would be good to add an example with desktop={false} and a right icon.
Today, we only have an example with {desktop=true}.

[birnam]

Sure @oliviertassinari I'll get that to you asap

[birnam]

PR @oliviertassinari : #2589