Add a Comma token.

Author: SimonSapin

ast.rs

@@ -36,6 +36,7 @@ pub enum ComponentValue {
     WhiteSpace,
     Colon,  // :
     Semicolon,  // ;
+    Comma,  // ,
     IncludeMath, // ~=
     DashMatch, // |=
     PrefixMatch, // ^=

tests.rs

@@ -312,6 +312,7 @@ impl ToJson for ComponentValue {
             WhiteSpace => JString(~" "),
             Colon => JString(~":"),
             Semicolon => JString(~";"),
+            Comma => JString(~","),
             IncludeMath => JString(~"~="),
             DashMatch => JString(~"|="),
             PrefixMatch => JString(~"^="),

tokenizer.rs

@@ -106,6 +106,7 @@ pub fn next_component_value(parser: &mut Parser) -> Option<(ComponentValue, Sour
                 Delim(c)
             }
         },
+        ',' => { parser.position += 1; Comma },
         '-' => {
             if (
                 parser.position + 1 < parser.length