Reapply "Support for precise stepping in functions compiled before debugging was started (step 2)"

src/debug.h

 // 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 791 matching lines @@
     } else if ((event == v8::ScriptCollected) &&
                !FLAG_debug_script_collected_events) {
       return false;
     }
 
     // Currently argument event is not used.
     return !compiling_natives_ && Debugger::IsDebuggerActive();
   }
 
   void set_compiling_natives(bool compiling_natives) {
-    Debugger::compiling_natives_ = compiling_natives;
+    compiling_natives_ = compiling_natives;
   }
   bool compiling_natives() const { return compiling_natives_; }
   void set_loading_debugger(bool v) { is_loading_debugger_ = v; }
   bool is_loading_debugger() const { return is_loading_debugger_; }
+  void set_force_debugger_active(bool force_debugger_active) {
+    force_debugger_active_ = force_debugger_active;
+  }
+  bool force_debugger_active() const { return force_debugger_active_; }
 
   bool IsDebuggerActive();
 
  private:
   explicit Debugger(Isolate* isolate);
 
   void CallEventCallback(v8::DebugEvent event,
                          Handle<Object> exec_state,
                          Handle<Object> event_data,
                          v8::Debug::ClientData* client_data);
   void CallCEventCallback(v8::DebugEvent event,
                           Handle<Object> exec_state,
                           Handle<Object> event_data,
                           v8::Debug::ClientData* client_data);
   void CallJSEventCallback(v8::DebugEvent event,
                            Handle<Object> exec_state,
                            Handle<Object> event_data);
   void ListenersChanged();
 
   Mutex* debugger_access_;  // Mutex guarding debugger variables.
   Handle<Object> event_listener_;  // Global handle to listener.
   Handle<Object> event_listener_data_;
   bool compiling_natives_;  // Are we compiling natives?
   bool is_loading_debugger_;  // Are we loading the debugger?
   bool never_unload_debugger_;  // Can we unload the debugger?
+  bool force_debugger_active_;  // Activate debugger without event listeners.
   v8::Debug::MessageHandler2 message_handler_;
   bool debugger_unload_pending_;  // Was message handler cleared?
   v8::Debug::HostDispatchHandler host_dispatch_handler_;
   Mutex* dispatch_handler_access_;  // Mutex guarding dispatch handler.
   v8::Debug::DebugMessageDispatchHandler debug_message_dispatch_handler_;
   MessageDispatchHelperThread* message_dispatch_helper_thread_;
   int host_dispatch_micros_;
 
   DebuggerAgent* agent_;
 
@@ skipping 204 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MessageDispatchHelperThread);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_H_