Don't unload debug context after it was requested through public API

src/api.cc

 // Copyright 2009 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 4002 matching lines @@
 
 bool Debug::EnableAgent(const char* name, int port, bool wait_for_connection) {
   return i::Debugger::StartAgent(name, port, wait_for_connection);
 }
 
 void Debug::ProcessDebugMessages() {
   i::Execution::ProcessDebugMesssages(true);
 }
 
 Local<Context> Debug::GetDebugContext() {
-  i::EnterDebugger debugger;
-  return Utils::ToLocal(i::Debug::debug_context());
+  ENTER_V8;
+  return Utils::ToLocal(i::Debugger::GetDebugContext());
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
 
 Handle<String> CpuProfileNode::GetFunctionName() const {
   IsDeadCheck("v8::CpuProfileNode::GetFunctionName");
   const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
@@ skipping 204 matching lines @@
 
 
 char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
   HandleScopeImplementer* thread_local =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   thread_local->IterateThis(v);
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal