node: Fix a compose_actions test.

This was apparently wrong in 207d7a8ee6.

frontend_tests/node_tests/compose_actions.js

@@ -275,7 +275,7 @@ run_test('quote_and_reply', () => {
 
     compose_ui.replace_syntax = function (syntax, replacement) {
         assert.equal(syntax, '[Quoting…]');
-        assert.equal(replacement, 'Testing.');
+        assert.equal(replacement, '```quote\nTesting.\n```');
     };
 
     var opts = {