title: Chrome extensions do not respect browser_specific_settings
body: <p>The W3C Browser Extensions Community Groups has been working for a while on compatibility between browser extensions on different platforms (Chrome/Firefox/Edge/Opera/Etc.). </p>
  
  <p>They have a <a href="https://browserext.github.io/browserext/#list-of-keys" rel="noreferrer">list of keys</a> which should be safe to use. An important one being <code>browser_specific_settings</code> so you can specify proprietary settings for different browsers without the manifest being marked as ill-formed.</p>
  
  <p>I need to add an ID for my Firefox addon under this key, but <strong>Chrome is not supporting this</strong> out of the box and shows an error if the extension is installed - <strong>Is there a way to tell Chrome to ignore this key?</strong> (without scaring the user that the extension is broken when it isn't)</p>