[WIP] Simplify now that promise cleans up canceller function

Refs reactphp/promise#119

Author: clue

src/functions.php

@@ -13,8 +13,6 @@ function timeout(PromiseInterface $promise, $time, LoopInterface $loop)
     // thus leaving responsibility to the input promise.
     $canceller = null;
     if ($promise instanceof CancellablePromiseInterface) {
-        // pass promise by reference to clean reference after cancellation handler
-        // has been invoked once in order to avoid garbage references in call stack.
         $canceller = function () use (&$promise) {
             $promise->cancel();
             $promise = null;
@@ -64,8 +62,7 @@ function resolve($time, LoopInterface $loop)
             $resolve($time);
         });
     }, function () use (&$timer, $loop) {
-        // cancelling this promise will cancel the timer, clean the reference
-        // in order to avoid garbage references in call stack and then reject.
+        // cancelling this promise will cancel the timer and reject
         $loop->cancelTimer($timer);
         $timer = null;