Fix custom properties for browsers

[sofiyareverse]

Custom properties does not work correct for Chrome and Firefox Browsers. It returns 'undefined' and [object Object] from client side.

To reproduce it just add 'data-custom-properties' to your option and check it in Chrome or Firefox like that: <option value="1" data-custom-properties='<span>Primary</span>'>1</option>

This small change fixes custom properties fields for browsers. Without it only Safari supports custom properties.

• [ x ] Bug fix (non-breaking change which fixes an issue)
• [ x ] My code follows the code style of this project.

[christiaan]

We've ran into this as well. This used to work in 9.0.1

[mtriff]

I believe this was resolved by #1001 and should be fixed in the next release.