Fixes for 1750 roll

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 281 matching lines @@
   [Suppressed] boolean send(ArrayBufferView data);
   [Suppressed] boolean send(Blob data);
   [Suppressed] boolean send(DOMString data);
 
   [Custom] void send(DOMString data);
   [Custom] void send(Blob data);
   [Custom] void send(ArrayBuffer data);
   [Custom] void send(ArrayBufferView data);
 };
 
-[Supplemental]
+[Supplemental, Constructor]
 interface XMLHttpRequest {
    [Custom] void send();
    [Custom] void send(ArrayBuffer data); // FIXME: this should be eventually deprecated.
    [Custom] void send(ArrayBufferView data);
    [Custom] void send(Blob data);
    [Custom] void send(Document data);
    [Custom] void send([StrictTypeChecking] DOMString data);
    [Custom] void send(FormData data);
 };
 
@@ skipping 40 matching lines @@
 [Suppressed]
 interface TextEncoder {};
 
 [Suppressed]
 interface TextDecoder {};
 
 [Supplemental]
 interface Window : EventTarget {};
 
 Element implements GlobalEventHandlers;