Edit: may not work after iOS 10, please see touch-action based solution below.
Your code is displaying attribute double quotes as fancy double quotes. If the fancy quotes are present in your actual source code I would guess that is the problem.
This works for me on Mobile Safari in iOS 4.2.
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />