code: function getInstanceBindingMap(content, delegate_) {
      var contentId = getContentUid(content);
      if (delegate_) {
        var map = delegate_.bindingMaps[contentId];
        if (!map) {
          map = delegate_.bindingMaps[contentId] =
              createInstanceBindingMap(content, delegate_.prepareBinding) || [];
        }
        return map;
      }
  
      var map = content.bindingMap_;
      if (!map) {
        map = content.bindingMap_ =
            createInstanceBindingMap(content, undefined) || [];
      }
      return map;
    }
docs: Each delegate is associated with a set of bindingMaps, one for each content which may be used by a template. The intent is that each binding delegate gets the opportunity to prepare the instance (via the prepare* delegate calls) once across all uses. TODO(rafaelw): Separate out the parse map from the binding map. In the current implementation, if two delegates need a binding map for the same content, the second will have to reparse.