Popup Title Padding

[codylawson]

https://github.com/Esri/dojo-theme-flat/blob/master/STYLUS/esri/dijit/css/Popup.styl#L80
https://github.com/Esri/dojo-theme-flat/blob/master/STYLUS/esri/dijit/css/Popup.styl#L418

In Popup.styl there's a padding rule for .titlePane that is set to auto, which isn't a valid value for padding. This rule is normally just ignored and doesn't seem to cause a problem, unless the stylesheets are run through a minifier like cssmin, in which case the padding rules are merged, i.e.:

padding: 6px;
padding-right: auto;

becomes:

padding: 6px auto 6px;

Is there a reason we're using auto? Should it be inherit or initial instead?