Move the thread local functions to the Thread class in runtime/platform

runtime/platform/thread.h

Index: runtime/platform/thread.h
diff --git a/runtime/platform/thread.h b/runtime/platform/thread.h
index 603949e9ca7f3570dd03d2d98eb74659a2184584..e4c3214cf7ba2d818e2c4260845eef226a3fd983 100644
--- a/runtime/platform/thread.h
+++ b/runtime/platform/thread.h
@@ -22,12 +22,21 @@ namespace dart {
 
 class Thread {
  public:
+  static ThreadLocalKey kUnsetThreadLocalKey;
+
   typedef void (*ThreadStartFunction) (uword parameter);
 
   // Start a thread running the specified function. Returns 0 if the
   // thread started successfuly and a system specific error code if
   // the thread failed to start.
   static int Start(ThreadStartFunction function, uword parameters);
+
+  static ThreadLocalKey CreateThreadLocal();
+  static void DeleteThreadLocal(ThreadLocalKey key);
+  static uword GetThreadLocal(ThreadLocalKey key) {
+    return ThreadInlineImpl::GetThreadLocal(key);
+  }
+  static void SetThreadLocal(ThreadLocalKey key, uword value);
 };