Vertical scrollbar width is not calculated on zoom change

[MichalJakubeczy]

Scrollbar width is calculated when grid is initialized via

Steps to reporoduce the bug:

1. Open http://plnkr.co/edit/Jlx891kOcOX39c1t9EpL?p=preview ... so far so good, grid's last column is right near scrollbar
   

2. Zoom in (e.g. to 200%) and you can see there is a space between last column's end and scrollbar
   

3. Zoom out (e.g. 50%) and you can see that part of last column is behind vertical scrollbar
   

Problem can be reproduced in Chrome or Firefox. In IE it works fine.

The problem is that:
self.scrollbarWidth = gridUtil.getScrollbarWidth();

is called on initialization only. It has to be also handled when zoom is changed (window resize maybe?). Because scrollbar width may vary depending on zoom level.