jquery/jquery — pull request #748 by rewish (2012-04-22 01:22:21+00:00)
Title: Fix return value of elem.css('background-position')

Fixed the undefined value in "IE<9",
And fixed a background-position bug in IE9.

#### Details of the background-position bug in IE9:

1. Set the background-position value by non-inline CSS
2. Set the background-* value
3. The background-position value is changed to "0% 0%"

```html

```