Forgot to say "public" in "class nsPropertiesFactory : nsIFactory".

This caused it to fail on Linux, but not on Windows. Go figure. Sigh.

base/src/nsProperties.h

@@ -21,7 +21,7 @@
 
 #include "nsIFactory.h"
 
-class nsPropertiesFactory : nsIFactory
+class nsPropertiesFactory : public nsIFactory
 {
 public:
   nsPropertiesFactory();

xpcom/ds/nsProperties.h

@@ -21,7 +21,7 @@
 
 #include "nsIFactory.h"
 
-class nsPropertiesFactory : nsIFactory
+class nsPropertiesFactory : public nsIFactory
 {
 public:
   nsPropertiesFactory();