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

client/dom/generated/src/frog/Float64Array.dart

 
 class _Float64ArrayJs extends _ArrayBufferViewJs implements Float64Array, List<num> native "*Float64Array" {
 
   factory Float64Array(int length) =>  _construct_Float64Array(length);
 
   factory Float64Array.fromList(List<num> list) => _construct_Float64Array(list);
 
   factory Float64Array.fromBuffer(ArrayBuffer buffer) => _construct_Float64Array(buffer);
 
   static _construct_Float64Array(arg) native 'return new Float64Array(arg);';
 
   static final int BYTES_PER_ELEMENT = 8;
 
-  int get length() native "return this.length;";
+  final int length;
 
   num operator[](int index) native "return this[index];";
 
   void operator[]=(int index, num value) native "this[index] = value";
   // -- start List<num> mixins.
   // num is the element type.
 
   // From Iterable<num>:
 
   Iterator<num> iterator() {
@@ skipping 56 matching lines @@
   }
   List<num> getRange(int start, int length) =>
       _Lists.getRange(this, start, length, <num>[]);
 
   // -- end List<num> mixins.
 
   void setElements(Object array, [int offset = null]) native;
 
   _Float64ArrayJs subarray(int start, [int end = null]) native;
 }