fixes offset with iframe in gecko & webkit; http://dev.jquery.com/ticket/3367

Author: fry

src/offset.js

@@ -16,10 +16,10 @@ if ( "getBoundingClientRect" in document.documentElement ) {
 			return jQuery.offset.bodyOffset( elem );
 		}
 
-		var box = elem.getBoundingClientRect(), doc = elem.ownerDocument, body = doc.body, docElem = doc.documentElement,
+		var box = elem.getBoundingClientRect(), doc = elem.ownerDocument, body = doc.body, docElem = doc.documentElement, win = doc.defaultView || self,
 			clientTop = docElem.clientTop || body.clientTop || 0, clientLeft = docElem.clientLeft || body.clientLeft || 0,
-			top  = box.top  + (self.pageYOffset || jQuery.support.boxModel && docElem.scrollTop  || body.scrollTop ) - clientTop,
-			left = box.left + (self.pageXOffset || jQuery.support.boxModel && docElem.scrollLeft || body.scrollLeft) - clientLeft;
+			top  = box.top  + (win.pageYOffset || jQuery.support.boxModel && docElem.scrollTop  || body.scrollTop ) - clientTop,
+			left = box.left + (win.pageXOffset || jQuery.support.boxModel && docElem.scrollLeft || body.scrollLeft) - clientLeft;
 
 		return { top: top, left: left };
 	};