Using W3C tests, IE9 RC (Internet Explorer) did try to prove its claim that it supports HTML 5 and CSS 3 almost 100%, but then HTML5Test and Caniuse did spoil the entire show. The score given by HTML5Test is definitely not so impressive for IE9 RC which awards Firefox 4 Beta with a score of 255 over 130 to the former.
Few facts about IE9 RC (even with a 100% W3C score)
- Dragging and dropping files from Desktop is not possible.
- CSS3 transitions, Text Shadow, Gradients, Border Image & Flex box model does not work.
- HTML5 History, ClassList & File API are not a reality yet.
- SMIL animations (SVG), WebGL (3D) and FormData are not supported.