Restore 'pointer' cursor on buttons

Normalize removed their opinionated cursor styling of buttons in [4.0.1](170455d6f6).

Follow-up-to: 1fd3a30a59

app/assets/stylesheets/common/foundation/base.scss

@@ -139,3 +139,13 @@ tr {
 ruby > rt {
   font-size: 72%; // ~10px with 14px base
 }
+
+// Buttons (was in normalized)
+// --------------------------------------------------
+
+button,
+html input[type="button"],
+input[type="reset"],
+input[type="submit"] {
+  cursor: pointer;
+}