Bug in CSSMin.php

I’ve stumbled upon a longstanding bug in CSSMin.php regarding @keyframe rules, resulting in invalid CSS code after minification. Here’s a patch:

--- CssMin.php.old      2014-07-31 23:54:20.988623978 +0200
+++ CssMin.php  2014-08-01 00:13:01.920546691 +0200
@@ -465,7 +465,7 @@
                                }
                        elseif ($class === "CssAtKeyframesStartToken")
                                {
-                               $r[] = $indent . "@keyframes \"" . $token->Name . "\"";
+                               $r[] = $indent . "@keyframes " . $token->Name . "";
                                $r[] = $this->indent . $indent . "{";
                                $level++;
                                }
@@ -1840,7 +1840,7 @@
                                }
                        elseif ($class === "CssAtKeyframesStartToken")
                                {
-                               $r[] = $indent . "@keyframes \"" . $token->Name . "\" {";
+                               $r[] = $indent . "@keyframes " . $token->Name . " {";
                                $level++;
                                }
                        elseif ($class === "CssAtMediaStartToken")
@@ -3325,7 +3325,7 @@
        public function apply(array &$tokens)
                {
                $r = 0;
-               $transformations = array("-moz-keyframes", "-webkit-keyframes");
+               $transformations = array("-moz-keyframes", "-webkit-keyframes", "-o-keyframes", "-ms-keyframes");
                for ($i = 0, $l = count($tokens); $i < $l; $i++)
                        {
                        if (get_class($tokens[$i]) === "CssAtKeyframesStartToken")
@@ -4435,7 +4435,7 @@
         */
        public function __toString()
                {
-               return "@" . $this->AtRuleName . " \"" . $this->Name . "\"{";
+               return "@" . $this->AtRuleName . " " . $this->Name . "{";
                }
        }

@@ -4574,6 +4574,23 @@
                        $this->parser->clearBuffer();
                        return $index + 15;
                        }
+               // Start of @keyframes at-rule block (@-ms-keyframes)
+               else if ($char === "@" && $state === "T_DOCUMENT" && strtolower(substr($this->parser->getSource(), $index, 14)) === "@-ms-keyframes")
+               {
+                       $this->atRuleName = "-ms-keyframes";
+                       $this->parser->pushState("T_AT_KEYFRAMES::NAME");
+                       $this->parser->clearBuffer();
+                       return $index + 14;
+                       }
+               // Start of @keyframes at-rule block (@-o-keyframes)
+               else if ($char === "@" && $state === "T_DOCUMENT" && strtolower(substr($this->parser->getSource(), $index, 13)) === "@-o-keyframes")
+                       {
+                       $this->atRuleName = "-o-keyframes";
+                       $this->parser->pushState("T_AT_KEYFRAMES::NAME");
+                       $this->parser->clearBuffer();
+                       return $index + 13;
+                       }
+
                // Start of @keyframes at-rule block (@-webkit-keyframes)
                elseif ($char === "@" && $state === "T_DOCUMENT" && strtolower(substr($this->parser->getSource(), $index, 18)) === "@-webkit-keyframes")
                        {

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