Meta: Add for-loop JavaScript test program

Author: https://github.com/deoxxa
Commit: 023d121e05
Pull-request: https://github.com/SerenityOS/serenity/pull/1425
Reviewed-by: https://github.com/sunverwerth

Base/home/anon/js/for-loop.js

@@ -0,0 +1,5 @@
+var x = 0;
+for (var i = 0; i !== 3; i += 1) {
+    x += 2;
+}
+x;