[Themes] ThemeView is missing jsdoc

[dangoor]

I missed in the initial review that some public functions in ThemeView are missing jsdoc.

cc @MiguelCastillo

[MiguelCastillo]

@dangoor Oh yeah! The only public interface with no jsdoc that will stay is updateScrollbars. All font stuff is going to be pushed over to the fonts API. Will make a PR for this.

[dangoor]

Oh right, I should have realized that was almost all font stuff.

[dangoor]

Fixed by #8459 (and the coming font API change)