testsuite: Fix corner case when testing repeats

When we test repeat nodes, make sure we round the size of the original
node up to an integer.
The reference image for the node is a rounded up, so when we generate a
new reference image we cannot deal with anything else.

Fixes huge-width test with --repeat.

testsuite/gsk/compare-render.c

@@ -353,6 +353,9 @@ main (int argc, char **argv)
           exit (77);
         }
 
+      node_bounds.size.width = ceil (node_bounds.size.width);
+      node_bounds.size.height = ceil (node_bounds.size.height);
+
       bounds.origin.x = 0.;
       bounds.origin.y = 0.;
       bounds.size.width = 2 * node_bounds.size.width;