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

client/dom/generated/src/frog/Uint32Array.dart

 
 class Uint32Array extends ArrayBufferView implements List<int> native "*Uint32Array" {
 
   factory Uint32Array(int length) =>  _construct(length);
 
   factory Uint32Array.fromList(List<int> list) => _construct(list);
 
   factory Uint32Array.fromBuffer(ArrayBuffer buffer) => _construct(buffer);
 
   static _construct(arg) native 'return new Uint32Array(arg);';
 
   static final int BYTES_PER_ELEMENT = 4;
 
-  int length;
+  int get length() native "return this.length;";
 
   int operator[](int index) native;
 
   void operator[]=(int index, int value) native;
 
   Uint32Array subarray(int start, [int end = null]) native;
 }