diff -r 000000000000 -r 6474c204b198 gfx/cairo/fix-win32-font-assertion.patch
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/cairo/fix-win32-font-assertion.patch	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+From: Jonathan Kew <jkew@mozilla.com>
+bug 838617 - don't assert equality with the key's hash unless it was actually initialized. r=roc
+
+diff --git a/gfx/cairo/cairo/src/cairo-win32-font.c b/gfx/cairo/cairo/src/cairo-win32-font.c
+--- a/gfx/cairo/cairo/src/cairo-win32-font.c
++++ b/gfx/cairo/cairo/src/cairo-win32-font.c
+@@ -2104,19 +2104,19 @@ cairo_win32_font_face_create_for_logfont
+     font_face = malloc (sizeof (cairo_win32_font_face_t));
+     if (!font_face) {
+         _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+ 	goto FAIL;
+     }
+ 
+     _cairo_win32_font_face_init_key (font_face, logfont, font);
+     _cairo_font_face_init (&font_face->base, &_cairo_win32_font_face_backend);
+-    assert (font_face->base.hash_entry.hash == key.base.hash_entry.hash);
+ 
+     if (!font) {
++        assert (font_face->base.hash_entry.hash == key.base.hash_entry.hash);
+         status = _cairo_hash_table_insert (hash_table,
+                                            &font_face->base.hash_entry);
+         if (unlikely (status))
+ 	    goto FAIL;
+     }
+ 
+ DONE:
+     if (!font) {