gecko-dev/gfx/cairo/cairo-mask-extends-bug.patch

diff --git a/gfx/cairo/cairo/src/cairo-image-surface.c b/gfx/cairo/cairo/src/cairo-image-surface.c
--- a/gfx/cairo/cairo/src/cairo-image-surface.c
+++ b/gfx/cairo/cairo/src/cairo-image-surface.c
@@ -1788,18 +1788,35 @@ static cairo_status_t
 					    cairo_boxes_t *boxes)
 {
     cairo_boxes_t clear;
     cairo_box_t box;
     cairo_status_t status;
     struct _cairo_boxes_chunk *chunk;
     int i;
 
-    if (boxes->num_boxes < 1 && clip_region == NULL)
-	return _cairo_image_surface_fixup_unbounded (dst, extents, NULL);
+    // If we have no boxes then we need to clear the entire extents
+    // because we have nothing to draw.
+    if (boxes->num_boxes < 1 && clip_region == NULL) {
+        int x = extents->unbounded.x;
+        int y = extents->unbounded.y;
+        int width = extents->unbounded.width;
+        int height = extents->unbounded.height;
+
+        pixman_color_t color = { 0 };
+        pixman_box32_t box = { x, y, x + width, y + height };
+
+        if (! pixman_image_fill_boxes (PIXMAN_OP_CLEAR,
+                                       dst->pixman_image,
+                                       &color,
+                                       1, &box)) {
+            return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+        }
+        return CAIRO_STATUS_SUCCESS;
+    }
 
     _cairo_boxes_init (&clear);
 
     box.p1.x = _cairo_fixed_from_int (extents->unbounded.x + extents->unbounded.width);
     box.p1.y = _cairo_fixed_from_int (extents->unbounded.y);
     box.p2.x = _cairo_fixed_from_int (extents->unbounded.x);
     box.p2.y = _cairo_fixed_from_int (extents->unbounded.y + extents->unbounded.height);