diff -r 000000000000 -r 6474c204b198 xpcom/base/nsErrorAssertsC.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/base/nsErrorAssertsC.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+#include "mozilla/Assertions.h"
+
+#include "nsError.h"
+
+/*
+ * No reason to pull in Assertions.h for every single file that includes
+ * nsError.h, so let's put this in its own .c file instead of in the .h.
+ */
+MOZ_STATIC_ASSERT(((nsresult)0) < ((nsresult)-1),
+                  "nsresult must be an unsigned type");
+MOZ_STATIC_ASSERT(sizeof(nsresult) == sizeof(uint32_t),
+                  "nsresult must be 32 bits");