Blocks until the extension is connectable in the firefox.

def _wait_until_connectable(self, timeout=30):
        """Blocks until the extension is connectable in the firefox."""
        count = 0
        while not utils.is_connectable(self.profile.port):
            if self.process.poll() is not None:
                # Browser has exited
                raise WebDriverException(
                    "The browser appears to have exited "
                    "before we could connect. If you specified a log_file in "
                    "the FirefoxBinary constructor, check it for details.")
            if count >= timeout:
                self.kill()
                raise WebDriverException(
                    "Can't load the profile. Possible firefox version mismatch. "
                    "You must use GeckoDriver instead for Firefox 48+. Profile "
                    "Dir: %s If you specified a log_file in the "
                    "FirefoxBinary constructor, check it for details."
                    % (self.profile.path))
            count += 1
            time.sleep(1)
        return True