[devtools] Fix for crash when opening full certificate details

This is a quickfix for the linked bug. The exact root cause (why the
certificate is empty) is unknown but it seems related to HTTP 302s.

Bug: 989478
Change-Id: I056ab03fb26d5acceb878826b856fed76af2fae5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1729228
Commit-Queue: Pâris Meuleman <pmeuleman@chromium.org>
Commit-Queue: Alexei Filippov <alph@chromium.org>
Auto-Submit: Pâris Meuleman <pmeuleman@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682770}

third_party/blink/renderer/devtools/front_end/security/SecurityPanel.js

@@ -47,6 +47,7 @@ Security.SecurityPanel = class extends UI.PanelWithSidebar {
     const certificateButton = UI.createTextButton(text, async e => {
       e.consume();
       const names = await SDK.multitargetNetworkManager.getCertificate(origin);
+      if (names.length > 0)
         InspectorFrontendHost.showCertificateViewer(names);
     }, 'origin-button');
     UI.ARIAUtils.markAsMenuButton(certificateButton);