Fix race condition in test-thread-termination.

test/cctest/test-thread-termination.cc

Index: test/cctest/test-thread-termination.cc
diff --git a/test/cctest/test-thread-termination.cc b/test/cctest/test-thread-termination.cc
index 1aa57e3081a5d779addf9fe141b77edc7a9ff623..cebabaa97e84fe0076da552d5cd6bd435f14f7bc 100644
--- a/test/cctest/test-thread-termination.cc
+++ b/test/cctest/test-thread-termination.cc
@@ -255,6 +255,10 @@ TEST(TerminateMultipleV8ThreadsDefaultIsolate) {
     threads[i]->Join();
     delete threads[i];
   }
+  {
+    v8::Locker locker;
+    v8::Locker::StopPreemption();
+  }
 
   delete semaphore;
   semaphore = NULL;