Support 'Conditional' idl attribute.

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

Index: client/dom/generated/src/frog/HTMLElement.dart
diff --git a/client/dom/generated/src/frog/HTMLElement.dart b/client/dom/generated/src/frog/HTMLElement.dart
index 80ea4254324b57f69c87916b771279440a566b55..4ebe126cc2fe9916b744a931a2968d2aceddeaf1 100644
--- a/client/dom/generated/src/frog/HTMLElement.dart
+++ b/client/dom/generated/src/frog/HTMLElement.dart
@@ -43,24 +43,6 @@ class _HTMLElementJs extends _ElementJs implements HTMLElement native "*HTMLElem
 
   bool get isContentEditable() native "return this.isContentEditable;";
 
-  String get itemId() native "return this.itemId;";
-
-  void set itemId(String value) native "this.itemId = value;";
-
-  _DOMSettableTokenListJs get itemProp() native "return this.itemProp;";
-
-  _DOMSettableTokenListJs get itemRef() native "return this.itemRef;";
-
-  bool get itemScope() native "return this.itemScope;";
-
-  void set itemScope(bool value) native "this.itemScope = value;";
-
-  _DOMSettableTokenListJs get itemType() native "return this.itemType;";
-
-  Object get itemValue() native "return this.itemValue;";
-
-  void set itemValue(Object value) native "this.itemValue = value;";
-
   String get lang() native "return this.lang;";
 
   void set lang(String value) native "this.lang = value;";