Bug 571992 - Make tabs on top be the default state on Windows. r=gavin

browser/base/content/browser.xul

@@ -506,6 +506,9 @@
            defaultmode="icons" mode="icons"
 #ifdef WINCE
            defaulticonsize="small" iconsize="small"
+#endif
+#ifdef XP_WIN
+           tabsontop="true"
 #endif
            persist="tabsontop">
     <!-- Menu -->