[css-transitions-2] Fix HTML validator warning.

Author: dbaron

css-transitions-2/Overview.bs

@@ -44,7 +44,7 @@ spec:web-animations-1; type:dfn;
     text:unresolved
 </pre>
 
-<style type="text/css">
+<style>
   table.event-state-transitions {
     width: 100%;
     border-spacing: 0px;