If you want this to work in non-WebKit browsers, you need to use a solution other than CSS.
There are some JavaScript solutions out there, or you can use SVG.
Here's a good blog post on how to do it: http://lea.verou.me/2012/05/text-masking-the-standards-way/
Using JavaScript has the downside of... using JavaScript, but at the end of the day this is only a decorative visual effect.