Port cssjanus 2.1.0 changes

Changes ported:
* Fix incorrect flipping with the general sibling combinator. wikimedia/node-cssjanus#86

Ref https://github.com/cssjanus/php-cssjanus/issues/31.

Author: jdforrester

src/CSSJanus.php

@@ -101,7 +101,7 @@ private static function buildPatterns() {
 		// Use "*+" instead of "*?" to avoid reaching the backtracking limit.
 		// <https://github.com/cssjanus/php-cssjanus/issues/14>, <https://phabricator.wikimedia.org/T215746#4944830>.
 		$patterns['url_chars'] = "(?:{$patterns['url_special_chars']}|{$patterns['nonAscii']}|{$patterns['escape']})*+";
-		$patterns['lookahead_not_open_brace'] = "(?!({$patterns['nmchar']}|\\r?\\n|\s|#|\:|\.|\,|\+|>|\(|\)|\[|\]|=|\*=|~=|\^=|'[^']*'|\"[^\"]*\"|" . self::TOKEN_COMMENT . ")*+{)";
+		$patterns['lookahead_not_open_brace'] = "(?!({$patterns['nmchar']}|\\r?\\n|\s|#|\:|\.|\,|\+|>|~|\(|\)|\[|\]|=|\*=|~=|\^=|'[^']*'|\"[^\"]*\"|" . self::TOKEN_COMMENT . ")*+{)";
 		$patterns['lookahead_not_closing_paren'] = "(?!{$patterns['url_chars']}{$patterns['valid_after_uri_chars']}\))";
 		$patterns['lookahead_for_closing_paren'] = "(?={$patterns['url_chars']}{$patterns['valid_after_uri_chars']}\))";
 		$patterns['noflip_single'] = "/({$patterns['noflip_annotation']}{$patterns['lookahead_not_open_brace']}[^;}]+;?)/i";

test/suites/CSSJanusTest.php

@@ -59,7 +59,7 @@ public function testTransform($input, $args, $output, $name) {
 	protected static function getSpec() {
 		static $json;
 		if ($json == null) {
-			$version = '2.0.0';
+			$version = '2.1.0';
 			$dir = dirname(__DIR__);
 			$file = "$dir/data-v$version.json";
 			if (!is_readable($file)) {