Allow CSSOM.CSSStyleSheet.prototype.insertRule to insert keyframe rules.

Fixes #40

Author: NV

lib/CSSStyleSheet.js

@@ -1,5 +1,6 @@
 //.CommonJS
 var CSSOM = {
+	parse: require("./parse"),
 	StyleSheet: require("./StyleSheet").StyleSheet,
 	CSSStyleRule: require("./CSSStyleRule").CSSStyleRule
 };
@@ -40,7 +41,7 @@ CSSOM.CSSStyleSheet.prototype.insertRule = function(rule, index) {
 	if (index < 0 || index > this.cssRules.length) {
 		throw new RangeError("INDEX_SIZE_ERR");
 	}
-	this.cssRules.splice(index, 0, CSSOM.CSSStyleRule.parse(rule));
+	this.cssRules.splice(index, 0, CSSOM.parse(rule));
 	return index;
 };