Don’t allow at-rule names to be functions

Makes it possible to parse most CSS3 media queries (MyIntervals#75), although not understand them.

Author: sabberworm

lib/Sabberworm/CSS/Parser.php

@@ -141,7 +141,7 @@ private function parseListItem(CSSList $oList, $bIsRoot = false) {
 
 	private function parseAtRule() {
 		$this->consume('@');
-		$sIdentifier = $this->parseIdentifier();
+		$sIdentifier = $this->parseIdentifier(false);
 		$iIdentifierLineNum = $this->iLineNo;
 		$this->consumeWhiteSpace();
 		if ($sIdentifier === 'import') {