Fix <input> style for check run filter

Screenshots https://imgur.com/a/Kp2Svtr

Release-Notes: skip
Change-Id: I2bc261dc1d82ea6cecf8c455df5f612708f1689d
(cherry picked from commit 9d1943f36963b17618fb8a7fc6a4a4b783de5c4f)
diff --git a/polygerrit-ui/app/elements/checks/gr-checks-runs.ts b/polygerrit-ui/app/elements/checks/gr-checks-runs.ts
index dd2b29f..797122e 100644
--- a/polygerrit-ui/app/elements/checks/gr-checks-runs.ts
+++ b/polygerrit-ui/app/elements/checks/gr-checks-runs.ts
@@ -475,6 +475,7 @@
     return [
       sharedStyles,
       fontStyles,
+      formStyles,
       css`
         :host {
           display: block;