Update library/extensions/comments-extensions.php

Changed type="text" to type="email" for the email input.
Changed type="text" to type="url" for the web address.
These HTML5 attributes are 100% backwards compatible and revert to type="text" for older browsers which ignore these input types. For modern browsers, the input types can be helpful such as validating email address before submitting and custom keyboard types on iOS devices.
Some info on the types here: http://diveintohtml5.info/forms.html