Bug fix: "width is null or not an object" from IE8 occasionally

Bug fix: "width is null or not an object" from IE8 occasionally.
![backgroundsize_bug](https://f.cloud.github.com/assets/1812260/700249/bb64367c-dd3e-11e2-8941-88e8731319df.png)

Additional:
Not properly working with jquery 1.9.1 + ie8 (undefined is null or not an object)
![1 9 1_bug](https://f.cloud.github.com/assets/1812260/700250/bb6980dc-dd3e-11e2-8ec0-839f5c509010.png)

Works well with jquery 1.10.1 + ie8