Fix syntax for Rsvg::Handle in test specs

[sparr]

Motivation

rake tests fail with a bunch of diffs like this:

@@ -252,7 +252,7 @@ cairo: scale([1.0, 1.0])
 cairo: rounded_rectangle([0, 0, 128.0, 128.0, 0, 0])
 cairo: clip([])
 cairo: translate([0, 0])
-cairo: render_rsvg_handle([Rsvg::Handlenil}])
+cairo: render_rsvg_handle([Rsvg::Handle, {id: nil}])
 cairo: restore([])
 cairo: save([])
 cairo: new_path([])

I'm not sure how those checks ever passed. The syntax is obviously wrong, including an unmatched }.