UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Steps to reproduce the problem:
1. Open dev tool settings
2. Switch 'Theme' to Dark
3. Open 'Sensors', 'Network conditions' or any other tab (other than settings) containing a html select
4. Toggle the select

What is the expected behavior?
The select options are very difficult to read due to the light text color on a white background.

What went wrong?
The select options should have a dark background inline with the dark theme. 

Did this work before? N/A 

Chrome version: 53.0.2785.143  Channel: n/a
OS Version: 10.0
Flash Version: Shockwave Flash 23.0 r0

settingsScreen.css contains styling to format the options (which is transformed with the theme) but select elements on other screens haven no styling.

To resolve:
Move `select option` styling from settingsScreen.css to a common (inspectorCommon.css) file with a generic (`chrome-select option, chrome-select optgroup`) selector.