Bug 1396453 - (speculative fix) - Remove the registered-fonts-changed notification observer when shutting down Mac font list, to avoid any risk of being called later during shutdown. r=jrmuizel

gfx/thebes/gfxMacPlatformFontList.mm

@@ -757,6 +757,11 @@ gfxMacPlatformFontList::gfxMacPlatformFontList() :
 
 gfxMacPlatformFontList::~gfxMacPlatformFontList()
 {
+    ::CFNotificationCenterRemoveObserver(::CFNotificationCenterGetLocalCenter(),
+                                         this,
+                                         kCTFontManagerRegisteredFontsChangedNotification,
+                                         0);
+
     if (mDefaultFont) {
         ::CFRelease(mDefaultFont);
     }