libdot/hterm: add missing dangling commas

Fixed linting problem with `eslint --fix`.

Bug: 999950
Change-Id: Ic7b4a379ddc2e65e5c069e658f02e46f769a2fa1
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/2153535
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/hterm/js/hterm_terminal.js b/hterm/js/hterm_terminal.js
index 3425465..4fda219 100644
--- a/hterm/js/hterm_terminal.js
+++ b/hterm/js/hterm_terminal.js
@@ -3902,7 +3902,7 @@
                           'A', 'B') +
             // Left/right arrow keys.
             deltaToArrows(delta.x, this.scrollPort_.characterSize.width,
-                          'C', 'D')
+                          'C', 'D'),
         );
 
         e.preventDefault();