Fast path for ThreadSpecific for main thread on TLS-slow platforms

third_party/WebKit/Source/wtf/ThreadingWin.cpp

Index: third_party/WebKit/Source/wtf/ThreadingWin.cpp
diff --git a/third_party/WebKit/Source/wtf/ThreadingWin.cpp b/third_party/WebKit/Source/wtf/ThreadingWin.cpp
index f8d87f820ca48c1ab946eba4cf8ed911404f72de..6f328ef1f558f2a45f90d09e860c8db0fe2fa65b 100644
--- a/third_party/WebKit/Source/wtf/ThreadingWin.cpp
+++ b/third_party/WebKit/Source/wtf/ThreadingWin.cpp
@@ -147,13 +147,13 @@ void unlockAtomicallyInitializedStaticMutex() {
 void initializeThreading() {
   // This should only be called once.
   DCHECK(!atomicallyInitializedStaticMutex);
+  WTFThreadData::initialize();
 
   // StringImpl::empty() does not construct its static string in a threadsafe
   // fashion, so ensure it has been initialized from here.
   StringImpl::empty();
   StringImpl::empty16Bit();
   atomicallyInitializedStaticMutex = new Mutex;
-  wtfThreadData();
   initializeDates();
   // Force initialization of static DoubleToStringConverter converter variable
   // inside EcmaScriptConverter function while we are in single thread mode.
@@ -161,7 +161,7 @@ void initializeThreading() {
 }
 
 ThreadIdentifier currentThread() {
-  return internal::currentThreadSyscall();
+  return WTFThreadData::current().threadId();
 }
 
 MutexBase::MutexBase(bool recursive) {