Function isThenable

lib/web/polyfill.js:1291–1295

(it)

  && Promise.resolve(test = new Promise(function(){})) == test
  || function(asap, RECORD){
    function isThenable(it){
      var then;
      if(isObject(it))then = it.then;
      return isFunction(then) ? then : false;
    }
    function handledRejectionOrHasOnRejected(promise){
      var record = promise[RECORD]
        , chain  = record.c