Stylesheet.addRule is broken in IE < 9

[hexinteractive]

IE only allows "Single contextual selectors" but xooie is sometimes passing selectors with multiple contexts. i.e.
.foo,
.bar {
color: pink;
}

[andrewlarkin]

We could mitigate this by adding the text to the <style> block directly. Of course, that results in a bunch of styles painted on the page, but it would work.