gsk: Preserve the antialiasing setting of the font

When we get an unhinted font for text node extents, don't change
the antialiasing setting. It doesn't affect the extents we get
here, but if we later need an unhinted font for rendering, the
one we create this way will be the right one, so it will already
exist.

gsk/gskrendernodeimpl.c

@@ -5825,7 +5825,7 @@ gsk_text_node_new (PangoFont              *font,
   PangoFont *unhinted;
   int n;
 
-  unhinted = gsk_get_hinted_font (font, CAIRO_HINT_STYLE_NONE, CAIRO_ANTIALIAS_GRAY);
+  unhinted = gsk_get_hinted_font (font, CAIRO_HINT_STYLE_NONE, CAIRO_ANTIALIAS_DEFAULT);
   pango_glyph_string_extents (glyphs, unhinted, &ink_rect, NULL);
   g_object_unref (unhinted);