Issue 2399 part 2: In debugger allow modifying local variable values

src/frames.cc

 // Copyright 2012 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 674 matching lines @@
   Object** fixed_base = &Memory::Object_at(
       fp() + JavaScriptFrameConstants::kFunctionOffset);
   Object** fixed_limit = &Memory::Object_at(fp());
   v->VisitPointers(fixed_base, fixed_limit);
 
   // Visit the return address in the callee and incoming arguments.
   IteratePc(v, pc_address(), code);
 }
 
 
+void JavaScriptFrame::SetParameterValue(int index, Object* value) const {
+  Memory::Object_at(GetParameterSlot(index)) = value;
+}
+
+
 bool JavaScriptFrame::IsConstructor() const {
   Address fp = caller_fp();
   if (has_adapted_arguments()) {
     // Skip the arguments adaptor frame and look at the real caller.
     fp = Memory::Address_at(fp + StandardFrameConstants::kCallerFPOffset);
   }
   return IsConstructFrame(fp);
 }
 
 
@@ skipping 731 matching lines @@
   ZoneList<StackFrame*> list(10, zone);
   for (StackFrameIterator it; !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame(), zone);
     list.Add(frame, zone);
   }
   return list.ToVector();
 }
 
 
 } }  // namespace v8::internal