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

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

 
 class _BiquadFilterNodeJs extends _AudioNodeJs implements BiquadFilterNode native "*BiquadFilterNode" {
 
   static final int ALLPASS = 7;
 
   static final int BANDPASS = 2;
 
   static final int HIGHPASS = 1;
 
   static final int HIGHSHELF = 4;
 
   static final int LOWPASS = 0;
 
   static final int LOWSHELF = 3;
 
   static final int NOTCH = 6;
 
   static final int PEAKING = 5;
 
-  _AudioParamJs get Q() native "return this.Q;";
+  final _AudioParamJs Q;
 
-  _AudioParamJs get frequency() native "return this.frequency;";
+  final _AudioParamJs frequency;
 
-  _AudioParamJs get gain() native "return this.gain;";
+  final _AudioParamJs gain;
 
-  int get type() native "return this.type;";
-
-  void set type(int value) native "this.type = value;";
+  int type;
 
   void getFrequencyResponse(_Float32ArrayJs frequencyHz, _Float32ArrayJs magResponse, _Float32ArrayJs phaseResponse) native;
 }