Highlight the default value in richcombo if default label is set

[Wiktor Walc]

Reported through support channel.

We found a small issue with font_defaultLabel and fontSize_defaultLabel. When these are set, the CKEditor does properly show them selected. But if you open the associated dropdown, they are not highlighted to indicate they are selected.

Screen capture 1: font and font size are properly displayed when using font_defaultLabel and fontSize_defaultLabel

Screen capture 2: font is not highlighted. Same thing for font size.

Screen capture 3: this is what we would expect when setting the font_defaultLabel setting