MDL-55224 core: Import PHP-CSS-Parser into core

Part of MDL-55071

lib/php-css-parser/CSSList/KeyFrame.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Sabberworm\CSS\CSSList;
+
+use Sabberworm\CSS\Property\AtRule;
+
+class KeyFrame extends CSSList implements AtRule {
+
+	private $vendorKeyFrame;
+	private $animationName;
+
+	public function __construct($iLineNo = 0) {
+		parent::__construct($iLineNo);
+		$this->vendorKeyFrame = null;
+		$this->animationName  = null;
+	}
+
+	public function setVendorKeyFrame($vendorKeyFrame) {
+		$this->vendorKeyFrame = $vendorKeyFrame;
+	}
+
+	public function getVendorKeyFrame() {
+		return $this->vendorKeyFrame;
+	}
+
+	public function setAnimationName($animationName) {
+		$this->animationName = $animationName;
+	}
+
+	public function getAnimationName() {
+		return $this->animationName;
+	}
+
+	public function __toString() {
+		return $this->render(new \Sabberworm\CSS\OutputFormat());
+	}
+
+	public function render(\Sabberworm\CSS\OutputFormat $oOutputFormat) {
+		$sResult = "@{$this->vendorKeyFrame} {$this->animationName}{$oOutputFormat->spaceBeforeOpeningBrace()}{";
+		$sResult .= parent::render($oOutputFormat);
+		$sResult .= '}';
+		return $sResult;
+	}
+
+	public function isRootList() {
+		return false;
+	}
+
+	public function atRuleName() {
+		return $this->vendorKeyFrame;
+	}
+
+	public function atRuleArgs() {
+		return $this->animationName;
+	}
+}