Remove bbox guard

It's probably not necessary.

This development still work in progress.

piet-gpu/shader/coarse.comp

@@ -413,9 +413,6 @@ void main() {
                 // should probably be stored in the annotated element.
                 uint path_ix = element_ix;
                 Path path = Path_read(PathRef(path_ix * Path_size));
-                // It may be we have a strong guarantee this will always be `true`, but
-                // I prefer not to take chances.
-                if (tile_x >= path.bbox.x && tile_x < path.bbox.z && tile_y >= path.bbox.y && tile_y < path.bbox.w) {
                 uint stride = path.bbox.z - path.bbox.x;
                 uint tile_subix = (tile_y - path.bbox.y) * stride + tile_x - path.bbox.x;
                 Tile tile = Tile_read(Tile_index(path.tiles, tile_subix));
@@ -429,7 +426,6 @@ void main() {
                     Cmd_Stroke_write(cmd_ref, cmd_stroke);
                     cmd_ref.offset += Cmd_size;
                 }
-                }
                 break;
             }
         }