eslint: enable prefer-rest-params check

The style guide says to use rest params instead of the automatic
arguments variable.

Change-Id: I29217b68b47bc166832e7734351f30cefd92e68d
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/2155978
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/hterm/js/hterm_test.js b/hterm/js/hterm_test.js
index e2cd273..4ba2b9c 100644
--- a/hterm/js/hterm_test.js
+++ b/hterm/js/hterm_test.js
@@ -17,9 +17,13 @@
 
 // Catch any random errors before the test runner runs.
 let earlyError = null;
-/** Catch any errors. */
-window.onerror = function() {
-  earlyError = Array.from(arguments);
+/**
+ * Catch any errors.
+ *
+ * @param {*} args Whatever arguments are passed in.
+ */
+window.onerror = function(...args) {
+  earlyError = Array.from(args);
 };
 
 /** Run the test framework once everything is finished. */