Validator rollup (#22925)

* cl/252836352 Revision bump for #22773

* cl/252863575 Add support for `itms-services` anchor protocol.

* cl/254001433 Revision bump for #22873

validator/validator-main.protoascii

@@ -26,7 +26,7 @@ min_validator_revision_required: 375
 # newer versions of the spec file. This is currently a Google internal
 # mechanism, validator.js does not use this facility. However, any
 # change to this file (validator-main.js) requires updating this revision id.
-spec_file_revision: 892
+spec_file_revision: 896
 
 styles_spec_url: "https://amp.dev/documentation/guides-and-tutorials/develop/style_and_layout/style_pages"
 script_spec_url: "https://amp.dev/documentation/guides-and-tutorials/learn/spec/amphtml#html-tags"
@@ -1806,6 +1806,9 @@ tags: {
       # Blackberry messenger
       # (http://devblog.blackberry.com/2015/02/cross-platform-sharing-with-bbm/)
       protocol: "bbmi"
+      # IOS over-the-air app installation
+      # (https://github.com/nifcblm/AHPP-iOS-App/wiki/How-to-distribute-enterprise-iOS-App)
+      protocol: "itms-services"
       protocol: "fb-me"
       protocol: "fb-messenger"
       protocol: "intent"