--- firefox-52.9.0esr/gfx/2d/HelpersCairo.h.old	2017-04-11 02:13:04.000000000 +0000
+++ firefox-52.9.0esr/gfx/2d/HelpersCairo.h	2018-12-08 18:45:01.880000000 +0000
@@ -160,7 +160,7 @@
     case SurfaceFormat::R5G6B5_UINT16:
       return CAIRO_FORMAT_RGB16_565;
     default:
-      gfxCriticalError() << "Unknown image format " << (int)format;
+      //gfxCriticalError() << "Unknown image format " << (int)format;
       return CAIRO_FORMAT_ARGB32;
   }
 }