Windows Phone 8.1 Update includes hundreds of Internet Explorer 11 enhancements that greatly increase compatibility with the mobile web.
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We updated the User Agent string in IE on Windows Phone to increase the number of sites that would correctly deliver the best mobile content.
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In Windows Phone 8.1 Update, we added a mapping of popular webkit-prefixed APIs to the standards based support already part of IE11. This means that sites that only send WebKit code are translated into standards based code as the page loads.
Unfortunately it’s us, web developers, that have forced the Internet Explorer team into doing this. Let’s just we hope we don’t make the same mistakes again.