Replaced Default with Initial value

Author: FlorianRappl

src/AngleSharp.Css/Converters/OptionValueConverter.cs

@@ -19,7 +19,7 @@ public ICssValue Convert(StringSource source)
         {
             if (source.IsDone || source.Current == Symbols.Comma)
             {
-                return new CssDefaultValue(_defaultValue);
+                return new CssInitialValue(_defaultValue);
             }
 
             return _converter.Convert(source);

src/AngleSharp.Css/Converters/ValueConverterExtensions.cs

@@ -63,15 +63,15 @@ public static IValueConverter Exclusive(this IValueConverter converter)
         public static IValueConverter Option(this IValueConverter converter, ICssValue defaultValue) =>
             new OptionValueConverter(converter, defaultValue);
 
-        public static String Join<T>(this T[] values, String separator)
+        public static String Join<T>(this IEnumerable<T> values, String separator)
             where T : ICssValue
         {
             var buffer = StringBuilderPool.Obtain();
             var previous = false;
 
-            for (var i = 0; i < values.Length; i++)
+            foreach (var value in values)
             {
-                var str = values[i]?.CssText;
+                var str = value?.CssText;
 
                 if (!String.IsNullOrEmpty(str))
                 {

src/AngleSharp.Css/Values/Multiples/CssTupleValue.cs

@@ -47,7 +47,9 @@ public CssTupleValue(T[] items = null, String separator = null)
         public String Separator => _separator;
 
         /// <inheritdoc />
-        public String CssText => _items.Join(_separator);
+        public String CssText => _items
+            .Where(m => m is CssInitialValue == false)
+            .Join(_separator);
 
         /// <inheritdoc />
         public Int32 Count => _items.Length;