[Select] selected option is unreadable for dark-themed UIs in Firefox

[jendowns]

Environment

Mac OS 10.14.6
Firefox 69.0.2

Detailed description

NOTE: this is in Firefox

After selecting an option with the Select component, the option is unreadable in Firefox:

Steps to reproduce the issue

1. Open Firefox
2. Go to the storybook (http://react.carbondesignsystem.com/?path=/story/select--default)
3. Select the g100 Carbon Theme in the bottom panel
4. Open + select an option in the Select component. While the Select is still active, you will see that the text is black and unreadable.