Revert "Implement typed array constructors."

client/dom/generated/src/frog/MediaList.dart

 
 class MediaList native "*MediaList" {
 
   int length;
 
   String mediaText;
 
   String operator[](int index) native;
 
-  void operator[]=(int index, String value) {
-    throw new UnsupportedOperationException("Cannot assign element of immutable List.");
-  }
-
   void appendMedium(String newMedium) native;
 
   void deleteMedium(String oldMedium) native;
 
   String item(int index) native;
 
   var dartObjectLocalStorage;
 
   String get typeName() native;
 }