This enables tracking of ARGB values for image masks, since some machines do

not use ARGB values.

See Mozilla bug #716462 - Performance regression with xBGR visual and no

RENDER extension.

We would like to try to get this upstream in the future.

diff --git a/gfx/cairo/cairo/src/cairo-xlib-surface.c b/gfx/cairo/cairo/src/cairo-xlib-surface.c

--- a/gfx/cairo/cairo/src/cairo-xlib-surface.c

+++ b/gfx/cairo/cairo/src/cairo-xlib-surface.c

@@ -2325,6 +2325,7 @@

                           cairo_region_t *clip_region)

 {

     cairo_image_surface_t *image;

+    cairo_format_masks_t image_masks;

     cairo_rectangle_int_t extents;

     cairo_status_t status;

     int tx, ty;

@@ -2341,6 +2342,16 @@

            (image->base.content & CAIRO_CONTENT_ALPHA) == 0)))

        return CAIRO_INT_STATUS_UNSUPPORTED;

+    if (image->base.backend->type == CAIRO_SURFACE_TYPE_IMAGE) {

+       if (_pixman_format_to_masks (image->pixman_format, &image_masks)) {

+           if (! ((image_masks.alpha_mask == surface->a_mask || surface->a_mask == 0) &&

+                  (image_masks.red_mask   == surface->r_mask || surface->r_mask == 0) &&

+                  (image_masks.green_mask == surface->g_mask || surface->g_mask == 0) &&

+                  (image_masks.blue_mask  == surface->b_mask || surface->b_mask == 0)))

+               return CAIRO_INT_STATUS_UNSUPPORTED;

+       }

+    }

+

     if (image->base.backend->type != CAIRO_SURFACE_TYPE_IMAGE) {

        if (image->base.backend->type == CAIRO_INTERNAL_SURFACE_TYPE_SNAPSHOT) {

            image = (cairo_image_surface_t *) ((cairo_surface_snapshot_t *) image)->target;