Allow function arguments to consist of multiple values

corpus/declarations.txt

@@ -20,6 +20,45 @@ a {
           (integer_value)
           (float_value)))))))
 
+=============================================
+Calls where each argument has multiple values
+=============================================
+
+div {
+  background: repeating-linear-gradient(red, orange 50px);
+  clip-path: polygon(50% 0%, 60% 40%, 100% 50%, 60% 60%, 50% 100%, 40% 60%, 0% 50%, 40% 40%);
+}
+
+---
+
+(stylesheet
+  (rule_set (selectors (tag_name)) (block
+    (declaration
+      (property_name)
+      (call_expression (function_name) (arguments
+        (plain_value)
+        (plain_value)
+        (integer_value (unit)))))
+    (declaration
+      (property_name)
+      (call_expression (function_name) (arguments
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))
+        (integer_value (unit))))))))
+
 ============================
 Color literals
 ============================

grammar.js

@@ -244,7 +244,7 @@ module.exports = grammar({
 
     arguments: $ => seq(
       token.immediate('('),
-      commaSep($._value),
+      commaSep(repeat1($._value)),
       ')'
     ),
 

src/grammar.json

@@ -1165,8 +1165,11 @@
               "type": "SEQ",
               "members": [
                 {
+                  "type": "REPEAT1",
+                  "content": {
                     "type": "SYMBOL",
                     "name": "_value"
+                  }
                 },
                 {
                   "type": "REPEAT",
@@ -1178,9 +1181,12 @@
                         "value": ","
                       },
                       {
+                        "type": "REPEAT1",
+                        "content": {
                           "type": "SYMBOL",
                           "name": "_value"
                         }
+                      }
                     ]
                   }
                 }