Move frog dart:dom from fields to getters/setters.

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

 
 class SVGLengthList native "*SVGLengthList" {
 
-  int numberOfItems;
+  int get numberOfItems() native "return this.numberOfItems;";
 
   SVGLength appendItem(SVGLength item) native;
 
   void clear() native;
 
   SVGLength getItem(int index) native;
 
   SVGLength initialize(SVGLength item) native;
 
   SVGLength insertItemBefore(SVGLength item, int index) native;
 
   SVGLength removeItem(int index) native;
 
   SVGLength replaceItem(SVGLength item, int index) native;
 
   var dartObjectLocalStorage;
 
   String get typeName() native;
 }