Issue 6822 - Report browser test errors

test/runners/webdriver.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 18 matching lines @@
                                  window._consoleLogs.log.push(msg);
                                  oldLog.call(this, msg);
                                };`)
     .then(() => driver.executeAsyncScript(realScript, scriptArgs))
     .then(() => driver.executeScript("return window._consoleLogs;"))
     .then(result =>
     {
       console.log(`\nBrowser tests in ${name}\n`);
       for (let item of result.log)
         console.log(item);
-      driver.quit();
-      if (result.failures != 0)
-        return Promise.reject(name);
+      return driver.quit().then(() =>
+      {
+        if (result.failures != 0)
+          throw name;
+      });
     }, error =>
     {
-      driver.quit();
-      return Promise.reject(error);
+      // This could be replaced by Promise.finally()
+      // once we require NodeJS >= 10
+      return driver.quit().then(() =>
+      {
+        throw error;
+      });
     });
 }
 
 module.exports.executeScript = executeScript;