Fix memory leak from d8 shell.

src/d8.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1003 matching lines @@
   // The stack size should be at least StackGuard::kLimitSize + some
   // OS-specific padding for thread startup code.
   options.stack_size = 2 << 20;  // 2 Mb seems to be enough
   return options;
 }
 
 
 void SourceGroup::ExecuteInThread() {
   Isolate* isolate = Isolate::New();
   do {
-    if (next_semaphore_ != NULL) next_semaphore_->Wait();
+    if (!next_semaphore_.is_empty()) next_semaphore_->Wait();
     {
       Isolate::Scope iscope(isolate);
       Locker lock(isolate);
       HandleScope scope;
       Persistent<Context> context = Shell::CreateEvaluationContext();
       {
         Context::Scope cscope(context);
         Execute();
       }
       context.Dispose();
     }
-    if (done_semaphore_ != NULL) done_semaphore_->Signal();
+    if (!done_semaphore_.is_empty()) done_semaphore_->Signal();
   } while (!Shell::options.last_run);
   isolate->Dispose();
 }
 
 
 void SourceGroup::StartExecuteInThread() {
-  if (thread_ == NULL) {
-    thread_ = new IsolateThread(this);
+  if (thread_.is_empty()) {
+    thread_ = i::SmartPointer<i::Thread>(new IsolateThread(this));
     thread_->Start();
   }
   next_semaphore_->Signal();
 }
 
 
 void SourceGroup::WaitForThread() {
-  if (thread_ == NULL) return;
+  if (thread_.is_empty()) return;
   if (Shell::options.last_run) {
     thread_->Join();
-    thread_ = NULL;
   } else {
     done_semaphore_->Wait();
   }
 }
 #endif  // V8_SHARED
 
 
 bool Shell::SetOptions(int argc, char* argv[]) {
   for (int i = 0; i < argc; i++) {
     if (strcmp(argv[i], "--stress-opt") == 0) {
@@ skipping 232 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif