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

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

Index: client/dom/generated/src/frog/SVGRect.dart
diff --git a/client/dom/generated/src/frog/SVGRect.dart b/client/dom/generated/src/frog/SVGRect.dart
index 003eb932d94f97ca12ca81f1dc19b6525a249a02..63ba1e4e0471216450a7c9179dc9e0446d137e67 100644
--- a/client/dom/generated/src/frog/SVGRect.dart
+++ b/client/dom/generated/src/frog/SVGRect.dart
@@ -1,19 +1,11 @@
 
 class _SVGRectJs extends _DOMTypeJs implements SVGRect native "*SVGRect" {
 
-  num get height() native "return this.height;";
+  num height;
 
-  void set height(num value) native "this.height = value;";
+  num width;
 
-  num get width() native "return this.width;";
+  num x;
 
-  void set width(num value) native "this.width = value;";
-
-  num get x() native "return this.x;";
-
-  void set x(num value) native "this.x = value;";
-
-  num get y() native "return this.y;";
-
-  void set y(num value) native "this.y = value;";
+  num y;
 }