[sfnt] Fix typo in clip box computation.

* src/sfnt/ttcolr.c (tt_face_get_color_glyph_clipbox): Use appropriate
scale factor for `yMin` and `yMax`.
diff --git a/src/sfnt/ttcolr.c b/src/sfnt/ttcolr.c
index 3dfd0c1..9a1e9a3 100644
--- a/src/sfnt/ttcolr.c
+++ b/src/sfnt/ttcolr.c
@@ -1404,11 +1404,12 @@
         font_clip_box.xMin = FT_MulFix( FT_NEXT_SHORT( p1 ),
                                         face->root.size->metrics.x_scale );
         font_clip_box.yMin = FT_MulFix( FT_NEXT_SHORT( p1 ),
-                                        face->root.size->metrics.x_scale );
+                                        face->root.size->metrics.y_scale );
         font_clip_box.xMax = FT_MulFix( FT_NEXT_SHORT( p1 ),
                                         face->root.size->metrics.x_scale );
         font_clip_box.yMax = FT_MulFix( FT_NEXT_SHORT( p1 ),
-                                        face->root.size->metrics.x_scale );
+                                        face->root.size->metrics.y_scale );
+
 
         /* Make 4 corner points (xMin, yMin), (xMax, yMax) and transform */
         /* them.  If we we would only transform two corner points and    */