Minor.

src/base/ftobjs.c

@@ -4107,6 +4107,7 @@
 
       FT_Bitmap_New( &bitmap );
 
+      /* this also converts the bitmap flow to `down' (i.e., pitch > 0) */
       err = FT_Bitmap_Convert( library, &slot->bitmap, &bitmap, 1 );
       if ( !err )
       {

src/pfr/pfrsbit.c

@@ -59,7 +59,7 @@
 
     if ( !decreasing )
     {
-      writer->line += writer->pitch * ( target->rows-1 );
+      writer->line += writer->pitch * ( target->rows - 1 );
       writer->pitch = -writer->pitch;
     }
   }

src/sfnt/pngshim.c

@@ -276,6 +276,7 @@
         goto DestroyExit;
       }
 
+      /* this doesn't overflow: 0x7FFF * 0x7FFF * 4 < 2^32 */
       size = map->rows * map->pitch;
 
       error = ft_glyphslot_alloc_bitmap( slot, size );