Flag all dfns as non-exported in release version of WebCrypto

See discussion in #1250

The definitions are extracted as "exported" because the release version of the
spec does not follow the usual dfn data model, but this creates duplication
issues in Bikeshed specs.

Valid references to the WebCrypto API do not use the xref mechanism in any case
so marking the definitions as private should not have any consequences for
existing specs.

src/postprocessing/patch-dfns.js

@@ -32,6 +32,16 @@ module.exports = {
         spec.dfns = spec.dfns.filter(dfn =>
           dfn.linkingText[0] !== 'MessageEventSource');
       }
+
+      // The /TR version of the WebCrypto API does not follow the usual dfn data
+      // model. Definitions get extracted as "exported" as a result. This
+      // creates collisions. The nightly version of the API respects the dfn
+      // data model, so let's force /TR dfns to be "non-exported" (most don't
+      // have the right "type" in any case). Also see discussion in:
+      // https://github.com/w3c/reffy/issues/1250
+      else if (spec.crawled.includes('/TR/WebCryptoAPI/')) {
+        spec.dfns.forEach(dfn => dfn.access = 'private');
+      }
     }
 
     return spec;