Sync the AnimationEvent and TransitionEvent interfaces with the specs

Source/core/events/TransitionEvent.idl

Index: Source/core/events/TransitionEvent.idl
diff --git a/Source/core/events/TransitionEvent.idl b/Source/core/events/TransitionEvent.idl
index 0f150f00c02e2710ff176a4941571d1ea32f866f..2cf948001c2560a37dac6803dd567c236ccccce1 100644
--- a/Source/core/events/TransitionEvent.idl
+++ b/Source/core/events/TransitionEvent.idl
@@ -24,13 +24,13 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-// http://dev.w3.org/csswg/css-transitions/#Events-TransitionEvent
+// http://dev.w3.org/csswg/css-transitions/#transition-events
 
 [
     Constructor(DOMString type, optional TransitionEventInit eventInitDict),
 ] interface TransitionEvent : Event {
     readonly attribute DOMString propertyName;
+    // TODO(philipj): elapsedTime should be float.
     readonly attribute double elapsedTime;
     readonly attribute DOMString pseudoElement;
 };
-