[Interpreter] Silence runtime errors in generate-bytecode-expectations.

test/cctest/interpreter/generate-bytecode-expectations.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cstring>
 #include <fstream>
 #include <vector>
 
 #include "test/cctest/interpreter/bytecode-expectations-printer.h"
 
@@ skipping 466 matching lines @@
     }
   }
   std::ostream& output_stream =
       options.write_to_stdout() ? std::cout : output_file_handle;
 
   GenerateExpectationsFile(output_stream, snippet_list, platform, options);
 
   return true;
 }
 
+void PrintMessage(v8::Local<v8::Message> message, v8::Local<v8::Value>) {
+  std::cerr << "INFO: " << *v8::String::Utf8Value(message->Get()) << '\n';
+}
+
+void DiscardMessage(v8::Local<v8::Message>, v8::Local<v8::Value>) {}
+
 void PrintUsage(const char* exec_path) {
   std::cerr
       << "\nUsage: " << exec_path
       << " [OPTIONS]... [INPUT FILES]...\n\n"
          "Options:\n"
          "  --help    Print this help message.\n"
          "  --verbose Emit messages about the progress of the tool.\n"
          "  --raw-js  Read raw JavaScript, instead of the output format.\n"
          "  --stdin   Read from standard input instead of file.\n"
          "  --rebaseline  Rebaseline input snippet file.\n"
@@ skipping 24 matching lines @@
 
 int main(int argc, char** argv) {
   ProgramOptions options = ProgramOptions::FromCommandLine(argc, argv);
 
   if (!options.Validate() || options.print_help()) {
     PrintUsage(argv[0]);
     return options.print_help() ? 0 : 1;
   }
 
   V8InitializationScope platform(argv[0]);
+  platform.isolate()->AddMessageListener(
+      options.rebaseline() && !options.verbose() ? PrintMessage

[rmcilroy, 2016/02/26 16:57:58]

Could you pull the "options.rebaseline() && !options.verbose()" into a local
variable to make this a bit more readable.

[Stefano Sanfilippo, 2016/02/26 17:01:06]

Done.

+                                                 : DiscardMessage);
 
   std::vector<std::string> snippet_list;
 
   if (options.read_from_stdin()) {
     // Rebaseline will never get here, so we will always take the
     // GenerateExpectationsFile at the end of this function.
     DCHECK(!options.rebaseline());
     ExtractSnippets(&snippet_list, std::cin, options.read_raw_js_snippet());
   } else {
     for (const std::string& input_filename : options.input_filenames()) {
@@ skipping 26 matching lines @@
     }
   }
 
   if (!options.rebaseline()) {
     if (!WriteExpectationsFile(snippet_list, platform, options,
                                options.output_filename())) {
       return 3;
     }
   }
 }