MAGETWO-36982: Create Search Module API to support search functionality.

 - MAGETWO-39542: Implement Product::search method

 - Fixed Batch

Author: aohorodnyk

app/code/Magento/Indexer/Model/SaveHandler/Batch.php

@@ -25,6 +25,8 @@ public function getItems(\Traversable $documents, $size)
                 $batch = [];
             }
         }
-        yield $batch;
+        if (count($batch) > 0) {
+            yield $batch;
+        }
     }
 }