LibWeb: Add list-style-type: lower-alpha and lower-latin support

They achieve the same, a list which markers are lowercase (latin)
characters.

Userland/Libraries/LibWeb/CSS/StyleValue.h

@@ -160,6 +160,8 @@ enum class ListStyleType {
     Square,
     Decimal,
     DecimalLeadingZero,
+    LowerAlpha,
+    LowerLatin,
 };
 
 enum class Overflow : u8 {