Bug 651480 - Only show the filter list when there are multiple filters on MacOS X. r=joshmoz

widget/src/cocoa/nsFilePicker.mm

@@ -368,7 +368,7 @@ nsFilePicker::GetLocalFiles(const nsString& inTitle, PRBool inAllowMultiple, nsC
   // are not available on 10.5 and without using them it happens to be buggy.
   int result;
   nsCocoaUtils::PrepareForNativeAppModalDialog();
-  if (nsToolkit::OnSnowLeopardOrLater()) {
+  if (mFilters.Length() > 1 && nsToolkit::OnSnowLeopardOrLater()) {
     // [NSURL initWithString:] (below) throws an exception if URLString is nil.
     if (!theDir) {
       theDir = @"";