typography field: font-style missing in CSS output if variant is regular/400

[rahulv3a]

Issue description:

If variant in typography field is 400 or regular, it doesn't output font-style: normal. This causes the element to inherit font-style from the parent elements which defeats the purpose of using typography field.

Version used:

Latest commit in develop branch, 556c23d.

Using theme_mods or options?

theme_mods

To reproduce the issue

Use one typography field on h1, h2, h3, h4, h5, h6 and another typography field on .widget-title. In the customizer, set font variant of h1, h2, h3, h4, h5, h6 to italic and .widget-title to regular. This would cause .widget-title to be italic as well.