Complete support for Windows TLS destructors

runtime/vm/os_win.cc

Index: runtime/vm/os_win.cc
diff --git a/runtime/vm/os_win.cc b/runtime/vm/os_win.cc
index 0e07cdf919ea5cf3f9c18d71d0554ee082d48af1..5af6c71c36815071648796d90f499bd1f7489d1e 100644
--- a/runtime/vm/os_win.cc
+++ b/runtime/vm/os_win.cc
@@ -368,6 +368,7 @@ void OS::InitOnce() {
   init_once_called = true;
   // Do not pop up a message box when abort is called.
   _set_abort_behavior(0, _WRITE_ABORT_MSG);
+  ThreadLocalData::InitOnce();
   MonitorWaitData::monitor_wait_data_key_ = OSThread::CreateThreadLocal();
   MonitorData::GetMonitorWaitDataForThread();
   LARGE_INTEGER ticks_per_sec;
@@ -380,6 +381,8 @@ void OS::InitOnce() {
 
 
 void OS::Shutdown() {
+  // TODO(zra): Enable once VM can shutdown cleanly.
+  // ThreadLocalData::Shutdown();
 }