Workaround bug 405384 (pngsuite reftest fails on Windows with slight color differences) by marking tests as fails-if(MOZ_WIDGET_TOOLKIT=="windows") These are not the crashtests you're looking for.

modules/libpr0n/test/reftest/pngsuite-zlib/reftest.list

@@ -9,10 +9,10 @@
 # See /mozilla/layout/tools/reftest/README.txt for more information.
 
 # z00n2c08 - color, no interlacing, compression level 0 (none)
-== z00n2c08.png z00n2c08.html
+fails-if(MOZ_WIDGET_TOOLKIT=="windows") == z00n2c08.png z00n2c08.html
 # z03n2c08 - color, no interlacing, compression level 3
-== z03n2c08.png z03n2c08.html
+fails-if(MOZ_WIDGET_TOOLKIT=="windows") == z03n2c08.png z03n2c08.html
 # z06n2c08 - color, no interlacing, compression level 6 (default)
-== z06n2c08.png z06n2c08.html
+fails-if(MOZ_WIDGET_TOOLKIT=="windows") == z06n2c08.png z06n2c08.html
 # z09n2c08 - color, no interlacing, compression level 9 (maximum) 
-== z09n2c08.png z09n2c08.html
+fails-if(MOZ_WIDGET_TOOLKIT=="windows") == z09n2c08.png z09n2c08.html

modules/libpr0n/test/reftest/reftest.list

@@ -17,4 +17,4 @@
 #include pngsuite-oddsizes/reftest.list
 #include pngsuite-palettes/reftest.list
 #include pngsuite-transparency/reftest.list
-#include pngsuite-zlib/reftest.list
+include pngsuite-zlib/reftest.list