Allow both "--no<flag>" and "--no-<flag>" to disable <flag>.

src/flags.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 250 matching lines @@
     args->Add(buffer.ToCString().Detach());
     JSArguments jsargs = *args_flag->args_variable();
     for (int j = 0; j < jsargs.argc(); j++) {
       args->Add(StrDup(jsargs[j]));
     }
   }
   return args;
 }
 
 
+inline char NormalizeChar(char ch) {
+  return ch == '_' ? '-' : ch;
+}
+
+
 // Helper function to parse flags: Takes an argument arg and splits it into
 // a flag name and flag value (or NULL if they are missing). is_bool is set
 // if the arg started with "-no" or "--no". The buffer may be used to NUL-
 // terminate the name, it must be large enough to hold any possible name.
 static void SplitArgument(const char* arg,
                           char* buffer,
                           int buffer_size,
                           const char** name,
                           const char** value,
                           bool* is_bool) {
   *name = NULL;
   *value = NULL;
   *is_bool = false;
 
   if (arg != NULL && *arg == '-') {
     // find the begin of the flag name
     arg++;  // remove 1st '-'
     if (*arg == '-') {
       arg++;  // remove 2nd '-'
       if (arg[0] == '\0') {
         const char* kJSArgumentsFlagName = "js_arguments";
         *name = kJSArgumentsFlagName;
         return;
       }
     }
     if (arg[0] == 'n' && arg[1] == 'o') {
       arg += 2;  // remove "no"
+      if (NormalizeChar(arg[0]) == '-') arg++;  // remove dash after "no".
       *is_bool = true;
     }
     *name = arg;
 
     // find the end of the flag name
     while (*arg != '\0' && *arg != '=')
       arg++;
 
     // get the value if any
     if (*arg == '=') {
       // make a copy so we can NUL-terminate flag name
       size_t n = arg - *name;
       CHECK(n < static_cast<size_t>(buffer_size));  // buffer is too small
       OS::MemCopy(buffer, *name, n);
       buffer[n] = '\0';
       *name = buffer;
       // get the value
       *value = arg + 1;
     }
   }
 }
 
 
-inline char NormalizeChar(char ch) {
-  return ch == '_' ? '-' : ch;
-}
-
-
 static bool EqualNames(const char* a, const char* b) {
   for (int i = 0; NormalizeChar(a[i]) == NormalizeChar(b[i]); i++) {
     if (a[i] == '\0') {
       return true;
     }
   }
   return false;
 }
 
 
@@ skipping 212 matching lines @@
 }
 
 
 void FlagList::EnforceFlagImplications() {
 #define FLAG_MODE_DEFINE_IMPLICATIONS
 #include "flag-definitions.h"
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 }
 
 } }  // namespace v8::internal