fix weixin browser bug

src/core.js

@@ -302,7 +302,7 @@ IScroll.prototype = {
 		this.scrollTo(newX, newY);	// ensures that the last position is rounded
 
 		// we scrolled less than 10 pixels
-		if ( !this.moved ) {
+		if ( !this.moved && typeof this.moved!='undefined') {
 			if ( this.options.tap ) {
 				utils.tap(e, this.options.tap);
 			}