Update the gr-avatar style to always have size 20px

Change-Id: If5cbfc1a7bf2b6366a19d945ea61d83dbf99a222
diff --git a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.html b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.html
index 7ed7962..4bf1f1b 100644
--- a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.html
+++ b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.html
@@ -33,10 +33,9 @@
         content: var(--account-label-suffix);
       }
       gr-avatar {
-        height: 1.3em;
-        width: 1.3em;
-        margin-right: var(--spacing-xs);
-        vertical-align: -.25em;
+        height: var(--line-height-normal);
+        width: var(--line-height-normal);
+        vertical-align: top;
       }
       .text {
         @apply --gr-account-label-text-style;