Comment 2 for bug 1044002

StacktraceTop:
 active_edges (polygon=0x7fc9327fad10, top=11242, left=0x7fc92033a880) at /build/buildd/cairo-1.12.2/src/cairo-polygon-intersect.c:1235
 intersection_sweep (polygon=0x7fc9327fad10, num_events=<optimized out>, start_events=<optimized out>) at /build/buildd/cairo-1.12.2/src/cairo-polygon-intersect.c:1271
 _cairo_polygon_intersect (a=a@entry=0x7fc9327fad10, winding_a=winding_a@entry=0, b=b@entry=0x7fc9327fa8c0, winding_b=<optimized out>) at /build/buildd/cairo-1.12.2/src/cairo-polygon-intersect.c:1466
 clip_and_composite_polygon (antialias=CAIRO_ANTIALIAS_DEFAULT, fill_rule=CAIRO_FILL_RULE_WINDING, polygon=0x7fc9327fad10, extents=0x7fc9327fb140, compositor=0x7fc96677e020) at /build/buildd/cairo-1.12.2/src/cairo-spans-compositor.c:861
 clip_and_composite_polygon (compositor=0x7fc96677e020, extents=0x7fc9327fb140, polygon=0x7fc9327fad10, fill_rule=CAIRO_FILL_RULE_WINDING, antialias=CAIRO_ANTIALIAS_DEFAULT) at /build/buildd/cairo-1.12.2/src/cairo-spans-compositor.c:819