Increase the default width of Font Size combo

[Wiktor Walc]

Note: this is a separate issue than #6162

When I test CKEditor in language other than English, the Size combo looks really ugly. Only two letters, or even one letter (in case of e.g. Japanese language) is displayed as a label for it. It's hard to understand what's there.

It's a little bit hard for me to agree that a solution for it is to ask anyone using non-English interface to manipulate CSS styles in order to have a nice-looking toolbar. Such basic functionality should be rather provided out of the box.

At the same time, we have 3 combos already with the same width: 60px, instead of 30px. If we changed the size of the "Size" combo to unify it with the rest, the problem with meaningless label would be solved.