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

tools/dom/idl/dart/dart.idl

Index: tools/dom/idl/dart/dart.idl
diff --git a/tools/dom/idl/dart/dart.idl b/tools/dom/idl/dart/dart.idl
index e2af8ea806526fee9d6c710d049e3fb946e6c3b1..cfb832bd8c9831a33415fa3715584e6f30e8f248 100644
--- a/tools/dom/idl/dart/dart.idl
+++ b/tools/dom/idl/dart/dart.idl
@@ -472,10 +472,6 @@ interface Screen {
     [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;
@@ -485,10 +481,6 @@ interface Screen {
     [Suppressed] readonly attribute SpeechInputResultList results;
 };
 
-[Supplemental] interface SpeechInputResultList {
-    [Suppressed] readonly attribute unsigned long length;
-};
-
 [Supplemental] interface AudioBufferSourceNode : AudioSourceNode {
     [Suppressed] readonly attribute AudioParam gain;
 };