Re-add font smoothing to gr-button

Was removed in I3de6102, but does make a noticeable difference.

Change-Id: Ie10792e906a9b824a9e52a362142070ea2ec499b

polygerrit-ui/app/elements/shared/gr-button/gr-button.html

@@ -39,6 +39,9 @@ limitations under the License.
         text-transform: none;
       }
       paper-button {
+        /* paper-button sets this to anti-aliased, which appears different than
+          bold font elsewhere on macOS. */
+        -webkit-font-smoothing: initial;
         align-items: center;
         background-color: var(--background-color);
         color: var(--text-color);