Make WheelEvent.delta{X,Y} return num, not int.

lib/html/idl/dart/dart.idl

 
 // This file introduces / supplements and forces Dart declarations.
 
 module default {
   ClientRectList implements sequence<ClientRect>;
   CSSRuleList implements sequence<CSSRule>;
   CSSValueList implements sequence<CSSValue>;
   DOMMimeTypeArray implements sequence<DOMMimeType>;
   DOMPluginArray implements sequence<DOMPlugin>;
   EntryArray implements sequence<Entry>;
@@ skipping 373 matching lines @@
 }
 
 module core {
   [Supplemental, Callback]
   interface RequestAnimationFrameCallback {
     // Webkit implements this as returning bool, but standard is void.
     [Suppressed] boolean handleEvent(in DOMTimeStamp time);
     [Custom] void handleEvent(in DOMTimeStamp time);
   };
 }
-
-module events {
-  [Supplemental]
-  interface WheelEvent {
-    [Suppressed] readonly attribute long wheelDelta;
-    [DartName=deltaX] readonly attribute long wheelDeltaX;
-    [DartName=deltaY] readonly attribute long wheelDeltaY;
-  };
-}