Fix more dates.

Author: Colin Robertson

docs/standard-library/binary-function-struct.md

@@ -1,7 +1,7 @@
 ---
 title: "binary_function Struct"
-ms.date: "11/04/2016"
-f1_keywords: ["functional/std::binary"]
+ms.date: "02/21/2019"
+f1_keywords: ["functional/std::binary_function"]
 helpviewer_keywords: ["binary_function class"]
 ms.assetid: 79b6d53d-644c-4add-b0ba-3a5f40f69c60
 ---

docs/standard-library/mem-fun-ref-t-class.md

@@ -1,6 +1,6 @@
 ---
 title: "mem_fun_ref_t Class"
-ms.date: "11/04/2016"
+ms.date: "02/21/2019"
 f1_keywords: ["functional/std::mem_fun_ref_t"]
 helpviewer_keywords: ["mem_fun_ref_t class"]
 ms.assetid: 7dadcac3-8d33-4e4b-a792-81bd53d3df39

docs/standard-library/mem-fun-t-class.md

@@ -1,6 +1,6 @@
 ---
 title: "mem_fun_t Class"
-ms.date: "11/04/2016"
+ms.date: "02/21/2019"
 f1_keywords: ["functional/std::mem_fun_t"]
 helpviewer_keywords: ["mem_fun_t class"]
 ms.assetid: 242566d4-750c-4c87-9d63-2e2c9d19ca2a