Fix very stupid test for bug 885067 that I pushed in rev 60d580712ec0. Clerical error on my part. no_r=orange.

js/src/jit-test/tests/arrow-functions/bug-885067-2.js

@@ -1,4 +1,4 @@
 (function() {
-    a = (b => eval("dis(); arguments"))();
+    a = (b => eval("arguments"))();
 })(1, 2, 3, 4);
-assertEq(a.length, 4);
+assertEq(a.length, 0);