fixing the toolbar issue. All the credit goes to biesi (he provided

the testcase for it)

widget/src/mac/nsNativeThemeQt.cpp

@@ -57,6 +57,7 @@
 nsNativeThemeQt::nsNativeThemeQt()
 {
     combo = new QComboBox((QWidget *)0);
+    combo->resize(0, 0);
     ThemeChanged();
 }