Add back invalid natives that couldn't be removed due to analyzer warnings.

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 454 matching lines @@
 
 [Supplemental] interface HTMLFormElement {
     void requestAutocomplete([Default=Undefined] optional Dictionary details);
     [Suppressed] void requestAutocomplete();
 };
 
 [Supplemental] interface AudioBufferSourceNode {
     [Suppressed] readonly attribute unsigned short playbackState;
 };
 
-[Supplemental] interface SVGElementInstanceList {
-    [Suppressed] readonly attribute unsigned long length;
-};
-
 [Supplemental] interface SpeechInputResult {
     [Suppressed] readonly attribute DOMString utterance;
     [Suppressed] readonly attribute float confidence;
 };
 
 [Supplemental] interface SpeechInputEvent : Event {
     [Suppressed] readonly attribute SpeechInputResultList results;
 };
 
-[Supplemental] interface SpeechInputResultList {
-    [Suppressed] readonly attribute unsigned long length;
-};
-
 [Supplemental] interface AudioBufferSourceNode : AudioSourceNode {
     [Suppressed] readonly attribute AudioParam gain;
 };
 
 Element implements GlobalEventHandlers;