bug 765700 - part 1 - trigger PresContext to reflow when Mac font list is updated. r=jdaggett

gfx/thebes/gfxMacPlatformFontList.mm

@@ -62,6 +62,7 @@
 #include "nsISimpleEnumerator.h"
 #include "nsCharTraits.h"
 
+#include "mozilla/Preferences.h"
 #include "mozilla/Telemetry.h"
 
 #include <unistd.h>
@@ -735,7 +736,7 @@ gfxMacPlatformFontList::InitFontList()
     // start the delayed cmap loader
     StartLoader(kDelayBeforeLoadingCmaps, kIntervalBetweenLoadingCmaps);
 
-	return NS_OK;
+    return NS_OK;
 }
 
 void
@@ -826,11 +827,15 @@ gfxMacPlatformFontList::GetStandardFamilyName(const nsAString& aFontName, nsAStr
 
 void
 gfxMacPlatformFontList::ATSNotification(ATSFontNotificationInfoRef aInfo,
-                                    void* aUserArg)
+                                        void* aUserArg)
 {
     // xxx - should be carefully pruning the list of fonts, not rebuilding it from scratch
-    gfxMacPlatformFontList *qfc = (gfxMacPlatformFontList*)aUserArg;
-    qfc->UpdateFontList();
+    static_cast<gfxMacPlatformFontList*>(aUserArg)->UpdateFontList();
+
+    // modify a preference that will trigger reflow everywhere
+    static const char kPrefName[] = "font.internaluseonly.changed";
+    bool fontInternalChange = Preferences::GetBool(kPrefName, false);
+    Preferences::SetBool(kPrefName, !fontInternalChange);
 }
 
 gfxFontEntry*