appDisplay: Apply the same padding to AllView and FrequentView

We add some horizontal padding to the AllView's content to make
sure content does not end up underneath the scrollbar; while this
is not required in case of the FrequentView which does not have
a scrollbar, applying the same padding ensures that both views
end up with the same spacing, which makes switching between them
less disruptive.

https://bugzilla.gnome.org/show_bug.cgi?id=694261

data/theme/gnome-shell.css

@@ -860,7 +860,8 @@ StScrollBar StButton#vhandle:active {
     padding: 4px 16px;
 }
 
-.all-apps > StBoxLayout {
+.all-apps > StBoxLayout,
+.frequent-apps > StBoxLayout {
     /* horizontal padding to make sure the scrollbar doesn't overlap content */
     padding: 0px 18px;
 }