The following test has been specifcally created to test the aforementioned IE8 Beta 1 regression bug.
In my example, I have speficied a padding-left value of 100% for the 'html' element, and given it a green (to consitute a pass) background color. The 'body' element has been, by default, left in the CSS flow with no width value specified, and assigned a red background color (to constitute a fail)
Therefore browsers which support padding for the 'html' element render the 100% padding value and the green background fills the entire page, constituting a pass.
IE8 Beta 1, which does not support padding for the 'html' element, cannot render the 'html' element's 100% padding value, meaning the 'body' element (with it's red background color), fills the entire page which constitutes a fail.