Execution: modified deferred behavior to be more predictable (+added more tests for them)

Author: vladar

docs/data-fetching.md

@@ -180,7 +180,7 @@ Here is an example of `BlogStory` resolver for field `author` that uses deferrin
     MyUserBuffer::add($blogStory['authorId']);
 
     return new GraphQL\Deferred(function () use ($blogStory) {
-        MyUserBuffer::loadOnce();
+        MyUserBuffer::loadBuffered();
         return MyUserBuffer::get($blogStory['authorId']);
     });
 }
@@ -242,6 +242,5 @@ Platforms supported out of the box:
 
 * [ReactPHP](https://github.com/reactphp/react) (requires **react/promise** as composer dependency):
   `GraphQL\GraphQL::setPromiseAdapter(new GraphQL\Executor\Promise\Adapter\ReactPromiseAdapter());`
-* HHVM: TODO
 
 To integrate other platform - implement `GraphQL\Executor\Promise\PromiseAdapter` interface. 

src/Executor/Promise/Adapter/SyncPromise.php

@@ -36,15 +36,6 @@ public static function runQueue()
         }
     }
 
-    public static function runNext()
-    {
-        $q = self::$queue;
-        if ($q && !$q->isEmpty()) {
-            $task = $q->dequeue();
-            $task();
-        }
-    }
-
     public $state = self::PENDING;
 
     public $result;

src/Executor/Promise/Adapter/SyncPromiseAdapter.php

@@ -133,7 +133,7 @@ public function wait(Promise $promise)
             !($dfdQueue->isEmpty() && $promiseQueue->isEmpty())
         ) {
             Deferred::runQueue();
-            SyncPromise::runNext();
+            SyncPromise::runQueue();
         }
 
         /** @var SyncPromise $syncPromise */