mootools/mootools-core — pull request #2409 by gonchuki (2012-08-16 20:27:18+00:00)
Title: Normalize backgroundPosition, fixes #2213 and #2295

several issues solved here:
- IE7 & 8 fail to return the `backgroundPosition` of an element when it was set on the stylesheet
- IE 7-8-9 (not sure about 10) return the top|right|bottom|left keywords when doing a `getStyle` if that keyword was used (7 and 8 only do it for `backgroundPosition[XY]`, they correctly normalize `backgroundPosition`)
- IE7, IE8, Chrome and Opera return an empty string on a `getStyle` over an element that has no `backgroundPosition` set

this patch normalizes all those scenarios so that all browsers return the same values (using the suggested normalization hash on #2213, plus other fixes).
If someone can test on IE10 it would be great, the fiddle I added to #2295 works fine after this patch is applied.