Fix command line parsing.

src/flags.cc

 // Copyright 2006-2008 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 <ctype.h>
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/assembler.h"
@@ skipping 354 matching lines @@
         }
       }
 
       // if we still need a flag value, use the next argument if available
       if (flag->type() != Flag::TYPE_BOOL &&
           flag->type() != Flag::TYPE_MAYBE_BOOL &&
           flag->type() != Flag::TYPE_ARGS &&
           value == NULL) {
         if (i < *argc) {
           value = argv[i++];
-        } else {
+        }
+        if (!value) {
           PrintF(stderr, "Error: missing value for flag %s of type %s\n"
                  "Try --help for options\n",
                  arg, Type2String(flag->type()));
           return_code = j;
           break;
         }
       }
 
       // set the flag
       char* endp = const_cast<char*>("");  // *endp is only read
@@ skipping 155 matching lines @@
 
 
 // static
 void FlagList::EnforceFlagImplications() {
 #define FLAG_MODE_DEFINE_IMPLICATIONS
 #include "src/flag-definitions.h"
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 }
 
 } }  // namespace v8::internal