Fix grammar to have more than one argument between parentheses

corpus/parentheses.txt

@@ -36,3 +36,17 @@ message(STATUS ((TEST))
     (argument (unquoted_argument)) (MISSING ")")
   )
 )
+
+===============================================
+Many arguments inside parentheses [parentheses]
+===============================================
+message(STATUS (TEST SECOND_TEST))
+---
+(source_file
+  (normal_command
+    (identifier)
+    (argument (unquoted_argument))
+    (argument (unquoted_argument))
+    (argument (unquoted_argument))
+  )
+)

grammar.js

@@ -35,7 +35,7 @@ module.exports = grammar({
 
     argument: ($) => choice($.bracket_argument, $.quoted_argument, $.unquoted_argument),
     _untrimmed_argument: ($) => choice(/\s/, $.bracket_comment, $.line_comment, $.argument, $._paren_argument),
-    _paren_argument: ($) => seq("(", $._untrimmed_argument, ")"),
+    _paren_argument: ($) => seq("(", repeat($._untrimmed_argument), ")"),
 
     quoted_argument: ($) => seq('"', optional($.quoted_element), '"'),
     quoted_element: ($) => repeat1(choice($.variable_ref, /[^\\"]/, $.escape_sequence)),

src/grammar.json

@@ -212,8 +212,11 @@
           "value": "("
         },
         {
+          "type": "REPEAT",
+          "content": {
             "type": "SYMBOL",
             "name": "_untrimmed_argument"
+          }
         },
         {
           "type": "STRING",