Drop navigations to NavigationEntry with invalid virtual URLs.

BUG=657720
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2452443002
Cr-Commit-Position: refs/heads/master@{#428056}
  net::EmbeddedTestServer* expired_https_server() {
    return expired_https_server_.get();
  }

  net::EmbeddedTestServer* expired_https_server() {
    return expired_https_server_.get();
  }
