To prepare for the Polymer 1.0.8, we need to remove or handle default values in Polymer properties

[StatelessCat]

In Polymer <1.0.8 :

Polymer({
  is: 'taaabs-xxx',
  properties: {
    trace: {
      type: Object,
      notify: true,
      reflectToAttribute: true,
      value: function() { return {}; },
      observer: 'traceChanged'
    },
   },
   traceChanged: function() {

   }
});

At the initialisation, Polymer is not calling the observer callback, after Polymer 1.0.8 it does (because of the default value: value: function() { return {}; }).