HTTP API: Add the missing 1xx HTTP response codes as constants of the WP_Http class, and add tests to ensure all available response codes are covered.

Fixes #36294


git-svn-id: https://develop.svn.wordpress.org/trunk@36749 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-http.php

@@ -21,6 +21,10 @@
 class WP_Http {
 
 	// Aliases for HTTP response codes.
+	const HTTP_CONTINUE                   = 100;
+	const SWITCHING_PROTOCOLS             = 101;
+	const PROCESSING                      = 102;
+
 	const OK                              = 200;
 	const CREATED                         = 201;
 	const ACCEPTED                        = 202;