Fix parsing trailing comma in comma-separated list

w3c/csswg-drafts#11254

Author: cdoublev

__tests__/value.js

@@ -4249,8 +4249,8 @@ describe('<media-query-list>', () => {
         expect(parse('<media-query-list>', 'all', false, mediaQueryContext)).toMatchObject(mediaQueryList)
     })
     test('valid', () => {
-        expect(parse('<media-query-list>', ';, 1, (condition)', true, mediaQueryContext))
-            .toBe('not all, not all, (condition)')
+        expect(parse('<media-query-list>', ';, 1, (condition),', true, mediaQueryContext))
+            .toBe('not all, not all, (condition), not all')
         expect(parse('<media-query-list>', 'all and (condition)', true, mediaQueryContext))
             .toBe('(condition)')
     })

lib/parse/parser.js

@@ -1,6 +1,6 @@
 
 const { createContext, getDeclarationValueDefinition, getRuleDefinition, getRuleType } = require('../utils/context.js')
-const { isCloseCurlyBrace, isColon, isDelimiter, isOpenCurlyBrace, isSemicolon, isSimpleBlock, isWhitespace } = require('../utils/value.js')
+const { isCloseCurlyBrace, isColon, isComma, isDelimiter, isOpenCurlyBrace, isSemicolon, isSimpleBlock, isWhitespace } = require('../utils/value.js')
 const Stream = require('./stream.js')
 const blocks = require('../values/blocks.js')
 const error = require('../error.js')
@@ -384,10 +384,12 @@ function parseComponentValue(input) {
  */
 function parseCommaSeparatedComponentValuesList(input) {
     input = normalizeIntoTokens(input)
-    const value = list([], ',')
-    while (!input.atEnd()) {
+    if (input.atEnd()) {
+        return list([], ',')
+    }
+    const value = list([consumeComponentValuesList(input, [','])], ',')
+    while (input.consume(isComma)) {
         value.push(consumeComponentValuesList(input, [',']))
-        input.consume()
     }
     return value
 }