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

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

 
 class _SVGMaskElementJs extends _SVGElementJs implements SVGMaskElement native "*SVGMaskElement" {
 
-  _SVGAnimatedLengthJs get height() native "return this.height;";
+  final _SVGAnimatedLengthJs height;
 
-  _SVGAnimatedEnumerationJs get maskContentUnits() native "return this.maskContentUnits;";
+  final _SVGAnimatedEnumerationJs maskContentUnits;
 
-  _SVGAnimatedEnumerationJs get maskUnits() native "return this.maskUnits;";
+  final _SVGAnimatedEnumerationJs maskUnits;
 
-  _SVGAnimatedLengthJs get width() native "return this.width;";
+  final _SVGAnimatedLengthJs width;
 
-  _SVGAnimatedLengthJs get x() native "return this.x;";
+  final _SVGAnimatedLengthJs x;
 
-  _SVGAnimatedLengthJs get y() native "return this.y;";
+  final _SVGAnimatedLengthJs y;
 
   // From SVGTests
 
-  _SVGStringListJs get requiredExtensions() native "return this.requiredExtensions;";
+  final _SVGStringListJs requiredExtensions;
 
-  _SVGStringListJs get requiredFeatures() native "return this.requiredFeatures;";
+  final _SVGStringListJs requiredFeatures;
 
-  _SVGStringListJs get systemLanguage() native "return this.systemLanguage;";
+  final _SVGStringListJs systemLanguage;
 
   bool hasExtension(String extension) native;
 
   // 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;
 }