Make Node.clone argument non-optional

tools/dom/idl/dart/dart.idl

 // This file introduces / supplements and forces Dart declarations.
 
 [Supplemental,
  Constructor]
 interface AudioContext {
   // TODO(ager): Auto-generate this custom method when the info about retaining
   // typed arrays is in the IDL.
   [Custom] void decodeAudioData(ArrayBuffer audioData, AudioBufferCallback successCallback, AudioBufferCallback errorCallback);
 };
 
@@ skipping 17 matching lines @@
   [Custom] void setDragImage(Element element, long x, long y);
 };
 
 [Supplemental]
 interface Document {
   [Suppressed] DOMObject getCSSCanvasContext(DOMString contextId, DOMString name, long width, long height);
   CanvasRenderingContext getCSSCanvasContext(DOMString contextId, DOMString name, long width, long height);
 };
 
 [Supplemental]
+interface Node {
+  Node cloneNode([Default=Undefined] optional boolean deep);
+};
+
+[Supplemental]
 interface ScriptProcessorNode {
   [Suppressed] attribute EventListener onaudioprocess;
   [Custom] void _setEventListener(EventListener eventListener);
 };
 
 /*
 // TODO(vsm): How should this interact with the new ChildNode and
 // ParentNode interfaces?
 // Force ElementTraversal. WebKit defines these directly.
 interface ElementTraversal : ChildNode, ParentNode {
@@ skipping 280 matching lines @@
   [CustomSetter] attribute DOMString search;
   [CustomSetter] attribute DOMString hash;
 };
 
 
 [Supplemental]
 interface Window : EventTarget {};
 
 [Supplemental]
 interface AbstractWorker : EventTarget {};