Cleanup Semaphore class.

src/d8-debug.h

Index: src/d8-debug.h
diff --git a/src/d8-debug.h b/src/d8-debug.h
index 276cbd82b80b2b5aba101fd775144d34884ecc0c..55876229a320d2bded2ea9f65c55713f4993fe2e 100644
--- a/src/d8-debug.h
+++ b/src/d8-debug.h
@@ -53,7 +53,7 @@ class RemoteDebugger {
   explicit RemoteDebugger(Isolate* isolate, int port)
       : isolate_(isolate),
         port_(port),
-        event_available_(i::OS::CreateSemaphore(0)),
+        event_available_(0),
         head_(NULL), tail_(NULL) {}
   void Run();
 
@@ -84,7 +84,7 @@ class RemoteDebugger {
   // the list is guarded by a mutex and a semaphore signals new items in the
   // list.
   i::Mutex event_access_;
-  i::Semaphore* event_available_;
+  i::Semaphore event_available_;
   RemoteDebuggerEvent* head_;
   RemoteDebuggerEvent* tail_;