Fix presubmit errors caused by updated depot tools

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 1008 matching lines @@
       case Debug::k_debug_break_slot_address:
         return reinterpret_cast<Address>(debug->debug_break_slot_address());
       case Debug::k_restarter_frame_function_pointer:
         return reinterpret_cast<Address>(
             debug->restarter_frame_function_pointer_address());
       default:
         UNREACHABLE();
         return NULL;
     }
   }
+
  private:
   Debug::AddressId id_;
 };
 
 // The optional thread that Debug Agent may use to temporary call V8 to process
 // pending debug requests if debuggee is not running V8 at the moment.
 // Techincally it does not call V8 itself, rather it asks embedding program
 // to do this via v8::Debug::HostDispatchHandler
 class MessageDispatchHelperThread: public Thread {
  public:
@@ skipping 11 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MessageDispatchHelperThread);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_H_