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

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

Index: client/dom/generated/src/frog/MutationEvent.dart
diff --git a/client/dom/generated/src/frog/MutationEvent.dart b/client/dom/generated/src/frog/MutationEvent.dart
index c7014dc8032d6ef4e1004b417f1b5e32ce22384c..6f850da9ef74a0594eb77d8d9d7bc599c179006d 100644
--- a/client/dom/generated/src/frog/MutationEvent.dart
+++ b/client/dom/generated/src/frog/MutationEvent.dart
@@ -7,15 +7,15 @@ class MutationEvent extends Event native "*MutationEvent" {
 
   static final int REMOVAL = 3;
 
-  int attrChange;
+  int get attrChange() native "return this.attrChange;";
 
-  String attrName;
+  String get attrName() native "return this.attrName;";
 
-  String newValue;
+  String get newValue() native "return this.newValue;";
 
-  String prevValue;
+  String get prevValue() native "return this.prevValue;";
 
-  Node relatedNode;
+  Node get relatedNode() native "return this.relatedNode;";
 
   void initMutationEvent(String type, bool canBubble, bool cancelable, Node relatedNode, String prevValue, String newValue, String attrName, int attrChange) native;
 }