Fixed a memory leak in v8 and another one in d8.

test/cctest/test-lockers.cc

Index: test/cctest/test-lockers.cc
diff --git a/test/cctest/test-lockers.cc b/test/cctest/test-lockers.cc
index b0f2b622363ed107d9a6193b5f13892483fa284f..cd3754651017a23703897e920fb58d8eb83ffea8 100644
--- a/test/cctest/test-lockers.cc
+++ b/test/cctest/test-lockers.cc
@@ -289,6 +289,7 @@ TEST(IsolateNestedLocking) {
     threads.Add(new IsolateNestedLockingThread(isolate));
   }
   StartJoinAndDeleteThreads(threads);
+  isolate->Dispose();
 }
 
 
@@ -584,6 +585,7 @@ TEST(LockUnlockLockMultithreaded) {
     threads.Add(new LockUnlockLockThread(isolate, context));
   }
   StartJoinAndDeleteThreads(threads);
+  isolate->Dispose();
 }
 
 class LockUnlockLockDefaultIsolateThread : public JoinableThread {