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

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

 
 class _SVGFEMergeElementJs extends _SVGElementJs implements SVGFEMergeElement native "*SVGFEMergeElement" {
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  _SVGAnimatedLengthJs get height() native "return this.height;";
+  final _SVGAnimatedLengthJs height;
 
-  _SVGAnimatedStringJs get result() native "return this.result;";
+  final _SVGAnimatedStringJs result;
 
-  _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 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;
 }