title: Protractor disable SELENIUM_PROMISE_MANAGER in one suite
body: <p>Due to <a href="https://github.com/angular/protractor/blob/master/docs/control-flow.md#disabling-the-control-flow" rel="nofollow noreferrer">disabling Selenium's control flow</a> in the future, I'm trying to write new specs using <code>async/await</code>. </p>
  
  <p>To do this, I have to use <code>SELENIUM_PROMISE_MANAGER: false</code> config option, which is unfortunately making my old specs that use Promise Manager fail.</p>
  
  <p>I've tried setting this option in <code>beforeAll</code>hook, but then I get the following error: </p>
  
  <p><code>TypeError: Unable to create a managed promise instance: the promise manager has been disabled by the SELENIUM_PROMISE_MANAGER environment variable: undefined</code></p>
  
  <p>If it's possible, I'd like to avoid having separate protractor conf files for async/non-async specs - it would make my grunt exec command even more complicated that it is now.</p>
  
  <p>Is there any other option to set this flag only for one or few specs/suites?</p>