Validator Rollup (ampproject#13045)

* Revision bump for ampproject#12862

* Revision bump for ampproject#13001

* Revision bump for ampproject#12906

validator/validator-main.protoascii

@@ -25,7 +25,7 @@ min_validator_revision_required: 295
 # 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: 554
+spec_file_revision: 557
 
 styles_spec_url: "https://www.ampproject.org/docs/guides/author-develop/responsive/style_pages"
 script_spec_url: "https://www.ampproject.org/docs/reference/spec#html-tags"