code: function(object, handler, acceptList) {
  
              var data = observed.get(object);
  
              if (data)
                  setHandler(object, data, handler, acceptList);
              else {
                  data = createObjectData(object);
                  setHandler(object, data, handler, acceptList);
                  
                  if (observed.size === 1)
                      // Let the observation begin!
                      nextFrame(runGlobalLoop);
              }
          }
docs: Functions for internal usage 
  Checks if the argument is an Array object. Polyfills Array.isArray.
  @function isArray
  @param {?*} object
  @returns {Boolean}