[chrome] box-shadow does not show above and below the arrow

Fixes Issue #3712.

UI Problem solved (when user resizes the window, box-shadow shows above and below the arrow).

![screenshot from 2013-10-04 01 38 51](https://f.cloud.github.com/assets/2356369/1265068/2d62c864-2c69-11e3-8753-c4d5beecacbc.png)