Revert "DO NOT CHECK IN test"

This reverts commit f3a68b50b64d5b979251f9595d941841ca1a7b30.

http2/http2_constants.h

diff --git a/http2/http2_constants.h b/http2/http2_constants.h
index 80c9158..9392006 100644
--- a/http2/http2_constants.h
+++ b/http2/http2_constants.h
@@ -6,7 +6,6 @@
 #define QUICHE_HTTP2_HTTP2_CONSTANTS_H_
 
 // Constants from the HTTP/2 spec, RFC 7540, and associated helper functions.
-// comment change for testing purposes only
 
 #include <cstdint>
 #include <iosfwd>