Change in preparation of fixing issue 19500.

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 15 matching lines @@
 interface Document {
   [Suppressed] DOMObject getCSSCanvasContext(DOMString contextId, DOMString name, long width, long height);
   CanvasRenderingContext getCSSCanvasContext(DOMString contextId, DOMString name, long width, long height);
   [Custom] Element createElement(DOMString tagName);
   [Custom] Element createElement(DOMString localName, DOMString typeExtension);
   [Custom] Element createElementNS(DOMString namespaceURI, DOMString qualifiedName);
   [Custom] Element createElementNS(DOMString namespaceURI, DOMString qualifiedName, DOMString typeExtension);
 };
 
 [Supplemental]
+interface FileReader {
+  [Suppressed] readonly attribute Object result;
+};
+
+[Supplemental]
 interface Node {
   [Custom] Node cloneNode([Default=Undefined] optional boolean deep);
   [Suppressed] readonly attribute Element nextElementSibling;
   [Suppressed] readonly attribute Element previousElementSibling;
 };
 
 [Supplemental]
 interface ScriptProcessorNode {
   [Suppressed] attribute EventListener onaudioprocess;
   [Custom] void _setEventListener(EventListener eventListener);
@@ skipping 433 matching lines @@
 
 [Supplemental] interface SpeechInputEvent : Event {
     [Suppressed] readonly attribute SpeechInputResultList results;
 };
 
 [Supplemental] interface AudioBufferSourceNode : AudioSourceNode {
     [Suppressed] readonly attribute AudioParam gain;
 };
 
 Element implements GlobalEventHandlers;