Down-integrate internal changes to github. (#5555)

* Down-integrate internal changes to github.

* fix python conformance test

* fix csharp conformance test

* add back java map_lite_test.proto's optimize for option

* fix php conformance test

js/binary/proto_test.js

diff --git a/js/binary/proto_test.js b/js/binary/proto_test.js
index 1618210..ae31c8d 100644
--- a/js/binary/proto_test.js
+++ b/js/binary/proto_test.js
@@ -661,4 +661,5 @@
     checkAllFields(msg, msg2);
 
   });
+
 });