Breakpoint position should be inside function body.

src/debug.cc

 // Copyright 2006-2008 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 152 matching lines @@
           }
         }
       }
     }
 
     // Check for break at return.
     if (RelocInfo::IsJSReturn(rmode())) {
       // Set the positions to the end of the function.
       if (debug_info_->shared()->HasSourceCode()) {
         position_ = debug_info_->shared()->end_position() -
-                    debug_info_->shared()->start_position();
+                    debug_info_->shared()->start_position() - 1;
       } else {
         position_ = 0;
       }
       statement_position_ = position_;
       break_point_++;
       return;
     }
   }
 }
 
@@ skipping 2812 matching lines @@
     {
       Locker locker;
       Debugger::CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal