Fix break position not to be outside of the script

src/runtime.cc

 // Copyright 2006-2009 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 9324 matching lines @@
     // Find position within function. The script position might be before the
     // source position of the first function.
     int position;
     if (shared->start_position() > source_position) {
       position = 0;
     } else {
       position = source_position - shared->start_position();
     }
     Debug::SetBreakPoint(shared, break_point_object_arg, &position);
     position += shared->start_position();
+
+    // The result position may become beyond script source end.
+    // This is expected when the function is toplevel. This may become
+    // a problem later when actual position gets converted into line/column.
+    if (shared->is_toplevel() && position == shared->end_position()) {
+      position = shared->end_position() - 1;
+    }
     return Smi::FromInt(position);
   }
   return  Heap::undefined_value();
 }
 
 
 // Clear a break point
 // args[0]: number: break point object
 static Object* Runtime_ClearBreakPoint(Arguments args) {
   HandleScope scope;
@@ skipping 1189 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal