Use fields in hidden native DOM classes instead of getters/setters.

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

Index: client/dom/generated/src/frog/SVGSymbolElement.dart
diff --git a/client/dom/generated/src/frog/SVGSymbolElement.dart b/client/dom/generated/src/frog/SVGSymbolElement.dart
index 40d47176b2aa6093a4cb9a6136236c58f11a8a4e..b18766dfb563931e8557bfc68719bd18eb1dd3e9 100644
--- a/client/dom/generated/src/frog/SVGSymbolElement.dart
+++ b/client/dom/generated/src/frog/SVGSymbolElement.dart
@@ -3,29 +3,25 @@ class _SVGSymbolElementJs extends _SVGElementJs implements SVGSymbolElement nati
 
   // From SVGLangSpace
 
-  String get xmllang() native "return this.xmllang;";
+  String xmllang;
 
-  void set xmllang(String value) native "this.xmllang = value;";
-
-  String get xmlspace() native "return this.xmlspace;";
-
-  void set xmlspace(String value) native "this.xmlspace = value;";
+  String xmlspace;
 
   // From SVGExternalResourcesRequired
 
-  _SVGAnimatedBooleanJs get externalResourcesRequired() native "return this.externalResourcesRequired;";
+  final _SVGAnimatedBooleanJs externalResourcesRequired;
 
   // From SVGStylable
 
-  _SVGAnimatedStringJs get className() native "return this.className;";
+  final _SVGAnimatedStringJs className;
 
-  _CSSStyleDeclarationJs get style() native "return this.style;";
+  final _CSSStyleDeclarationJs style;
 
   _CSSValueJs getPresentationAttribute(String name) native;
 
   // From SVGFitToViewBox
 
-  _SVGAnimatedPreserveAspectRatioJs get preserveAspectRatio() native "return this.preserveAspectRatio;";
+  final _SVGAnimatedPreserveAspectRatioJs preserveAspectRatio;
 
-  _SVGAnimatedRectJs get viewBox() native "return this.viewBox;";
+  final _SVGAnimatedRectJs viewBox;
 }