Issue 6090 - Silence warnings from the RSA signature tests

test/_common.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 401 matching lines @@
     Cr,
     XMLHttpRequest,
     Date: {
       now: () => currentTime
     }
   };
 };
 
 console.warn = console.log;
 
+exports.silenceWarnOutput = function(test, msg)
+{
+  let warnHandler = globals.console.warn;
+  globals.console.warn = s =>
+  {
+    if (s != msg)
+      warnHandler(s);
+  };
+  try
+  {
+    return test();
+  }
+  finally
+  {
+    globals.console.warn = warnHandler;
+  }
+};
+
 exports.silenceAssertionOutput = function(test, msg)
 {
   let msgMatch = new RegExp(`^Error: ${msg}[\r\n]`);
   let errorHandler = globals.console.error;
   globals.console.error = s =>
   {
     if (!msgMatch.test(s))
       errorHandler(s);
   };
   try
@@ skipping 21 matching lines @@
       }
     })
   };
 };
 
 exports.unexpectedError = function(error)
 {
   console.error(error);
   this.ok(false, "Unexpected error: " + error);
 };