fix #857 test.aria.utils.css.Effects in Firefox

The test was using backgroundPositionX/Y style properties
which are not standard, and not supported by Firefox.
fix #859 test.aria.utils.Dom failure in some browsers

Method `getStyle` was giving the wrong values for `"backgroundPositionX"` and `"backgroundPositionY"`.
On top of that, even on modern borwsers, a null value is returned in some cases even when a value is available.
fix test.aria.html.textinput.placeholder.PlaceholderTestCase randomly failed in IE9
fix #861 test.aria.templates.validation.errortext.ErrorTextTestCase failure in Chrome

The test was failing because the synthetic type (with the robot) was not working. Clicking on the field first makes it work.
doc `preloadSkinImages` writes to `<BODY>`

Close #854.
fix #863 test.aria.popups.Popup failure in IE7

The bean for popup configuration has also been updated.
v1.4.13