Print <undefined> in d8 when used as interactive shell.

src/d8.cc

 // 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 154 matching lines @@
   } else {
     Handle<Value> result = script->Run();
     if (result.IsEmpty()) {
       ASSERT(try_catch.HasCaught());
       // Print errors that happened during execution.
       if (report_exceptions && !FLAG_debugger)
         ReportException(&try_catch);
       return false;
     } else {
       ASSERT(!try_catch.HasCaught());
-      if (print_result && !result->IsUndefined()) {
+      if (!print_result) return true;
+      if (result->IsUndefined()) {
+        printf("<undefined>\n");
+      } else {
         // If all went well and the result wasn't undefined then print
         // the returned value.
         v8::String::Utf8Value str(result);
         const char* cstr = ToCString(str);
         printf("%s\n", cstr);
       }
       return true;
     }
   }
 }
@@ skipping 1110 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif