field_expandable_add -- dont xml serialize

Author: SharkPool-SP

core/field_expandable_add.js

@@ -57,6 +57,11 @@ Blockly.FieldExpandableAdd.fromJson = function(options) {
  */
 Blockly.FieldExpandableAdd.prototype.CURSOR = 'pointer';
 
+/**
+ * Dont serialize this field
+ */
+Blockly.FieldExpandableAdd.prototype.SERIALIZABLE = false;
+
 /**
  * Icon used by button
  */