Add isOpera, isIE is false if opera

std/js/Boot.hx

@@ -180,7 +180,8 @@ class Boot {
 
 	private static function __init() {
 		untyped {
-			Lib.isIE = (document.all != null);
+			Lib.isIE = (document.all != null && window.opera == null );
+			Lib.isOpera = (window.opera != null );
 			Array.prototype.copy = Array.prototype.slice;
 			Array.prototype.insert = function(i,x) {
 				this.splice(i,0,x);

std/js/Lib.hx

@@ -29,6 +29,7 @@ import js.Dom;
 class Lib {
 
 	public static var isIE : Bool;
+	public static var isOpera : Bool;
 	public static var document : Document = untyped __js__("document");
 	public static var window : Window = untyped __js__("window");