message: Removed redundant code
  Those fields are initialised when the StateContext is created
diff: @@ -64,9 +64,6 @@ class StateNavigator {
  stateContext.data = data;
  stateContext.hash = hash;
  stateContext.nextCrumb = new Crumb(data, state, url, this.stateHandler.getLink(state, data, hash), false, hash);
  - stateContext.previousState = null;
  - stateContext.previousData = {};
  - stateContext.previousUrl = null;
  if (stateContext.crumbs.length > 0) {
  var previousStateCrumb = stateContext.crumbs.slice(-1)[0];
  stateContext.previousState = previousStateCrumb.state;
  