Bug 1871187: prompt() goes through content analysis r=Gijs

Adds another text-paste case to content analysis, this time for the
prompt() command, which is not covered by the other clipboard cases
in bug 1871135.

Differential Revision: https://phabricator.services.mozilla.com/D197018

browser/components/contentanalysis/content/ContentAnalysis.sys.mjs

@@ -221,7 +221,7 @@ export const ContentAnalysis = {
       }
       case "dlp-request-made":
         {
-          const request = aSubj;
+          const request = aSubj.QueryInterface(Ci.nsIContentAnalysisRequest);
           if (!request) {
             console.error(
               "Showing in-browser Content Analysis notification but no request was passed"
@@ -272,7 +272,7 @@ export const ContentAnalysis = {
         }
         break;
       case "dlp-response":
-        const request = aSubj;
+        const request = aSubj.QueryInterface(Ci.nsIContentAnalysisResponse);
         // Cancels timer or slow message UI,
         // if present, and possibly presents the CA verdict.
         if (!request) {