Merge pull request #1454 from iamdoron/master

Use shift instead of splice (when possible) in queue

lib/internal/queue.js

@@ -65,7 +65,9 @@ export default function queue(worker, concurrency, payload) {
                 var task = tasks[i];
 
                 var index = indexOf(workersList, task, 0);
-                if (index >= 0) {
+                if (index === 0) {
+                    workersList.shift();
+                } else if (index > 0) {
                     workersList.splice(index, 1);
                 }