Bug 526586 - XULRunner crashes on startup on Windows r=bustage fix and at least agreement on the approach from dbaron

xpcom/threads/nsThreadManager.cpp

@@ -44,7 +44,10 @@
 #include "nsAutoPtr.h"
 #include "nsAutoLock.h"
 
-#ifdef NS_TLS
+#ifdef XP_WIN
+#include <windows.h>
+DWORD gTLSIsMainThreadIndex = TlsAlloc();
+#elif defined(NS_TLS)
 NS_TLS bool gTLSIsMainThread = false;
 #endif
 
@@ -106,7 +109,9 @@ nsThreadManager::Init()
   // GetIsMainThread calls that occur post-Shutdown.
   mMainThread->GetPRThread(&mMainPRThread);
 
-#ifdef NS_TLS
+#ifdef XP_WIN
+  TlsSetValue(gTLSIsMainThreadIndex, (void*) 1);
+#elif defined(NS_TLS)
   gTLSIsMainThread = true;
 #endif