Don't write magic numbers in script snapshots from gen_snapshot

runtime/bin/gen_snapshot.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 684 matching lines @@
 "   --package_root=<path>             Where to find packages, that is,       \n"
 "                                     package:...  imports.                  \n"
 "                                                                            \n"
 "   --packages=<packages_file>        Where to find a package spec file      \n"
 "                                                                            \n"
 "   --url_mapping=<mapping>           Uses the URL mapping(s) specified on   \n"
 "                                     the command line to load the           \n"
 "                                     libraries.                             \n"
 "                                                                            \n"
 " To create a core snapshot:                                                 \n"
-"   --snapshot-kind=core                                                     \n"
+"   --snapshot_kind=core                                                     \n"
 "   --vm_snapshot_data=<output-file>                                         \n"
 "   --isolate_snapshot_data=<output-file>                                    \n"
 "   [<dart-script-file>]                                                     \n"
 "                                                                            \n"
 " Writes a snapshot of <dart-script-file> to the specified snapshot files.   \n"
 " If no <dart-script-file> is passed, a generic snapshot of all the corelibs \n"
 " is created.                                                                \n"
 "                                                                            \n"
 " To create a script snapshot with respect to a given core snapshot:         \n"
-"   --snapshot-kind=script                                                   \n"
+"   --snapshot_kind=script                                                   \n"
 "   --vm_snapshot_data=<intput-file>                                         \n"
 "   --isolate_snapshot_data=<intput-file>                                    \n"
 "   --script_snapshot=<output-file>                                          \n"
 "   <dart-script-file>                                                       \n"
 "                                                                            \n"
 "  Writes a snapshot of <dart-script-file> to the specified snapshot files.  \n"
 "  If no <dart-script-file> is passed, a generic snapshot of all the corelibs\n"
 "  is created.                                                               \n"
 "                                                                            \n"
 " To create an AOT application snapshot as blobs suitable for loading with   \n"
 " mmap:                                                                      \n"
-"   --snapshot-kind=app-aot-blobs                                            \n"
+"   --snapshot_kind=app-aot-blobs                                            \n"
 "   --vm_snapshot_data=<output-file>                                         \n"
 "   --vm_snapshot_instructions=<output-file>                                 \n"
 "   --isolate_snapshot_data=<output-file>                                    \n"
 "   --isolate_snapshot_instructions=<output-file>                            \n"
 "   {--embedder_entry_points_manifest=<input-file>}                          \n"
 "   <dart-script-file>                                                       \n"
 "                                                                            \n"
 " To create an AOT application snapshot as assembly suitable for compilation \n"
 " as a static or dynamic library:                                            \n"
 " mmap:                                                                      \n"
-"   --snapshot-kind=app-aot-blobs                                            \n"
+"   --snapshot_kind=app-aot-blobs                                            \n"
 "   --assembly=<output-file>                                                 \n"
 "   {--embedder_entry_points_manifest=<input-file>}                          \n"
 "   <dart-script-file>                                                       \n"
 "                                                                            \n"
 " AOT snapshots require entry points manifest files, which list the places   \n"
 " in the Dart program the embedder calls from the C API (Dart_Invoke, etc).  \n"
 " Not specifying these may cause the tree shaker to remove them from the     \n"
 " program. The format of this manifest is as follows. Each line in the       \n"
 " manifest is a comma separated list of three elements. The first entry is   \n"
 " the library URI, the second entry is the class name and the final entry    \n"
@@ skipping 380 matching lines @@
   ASSERT(snapshot_kind == kScript);
   ASSERT(script_snapshot_filename != NULL);
 
   // First create a snapshot.
   uint8_t* buffer = NULL;
   intptr_t size = 0;
   Dart_Handle result = Dart_CreateScriptSnapshot(&buffer, &size);
   CHECK_RESULT(result);
 
   // Now write it out to the specified file.
-  WriteSnapshotFile(script_snapshot_filename, buffer, size, true);
+  WriteSnapshotFile(script_snapshot_filename, buffer, size, false);
 }
 
 
 static void CreateAndWritePrecompiledSnapshot(
     Dart_QualifiedFunctionName* standalone_entry_points) {
   ASSERT(IsSnapshottingForPrecompilation());
   Dart_Handle result;
 
   // Precompile with specified embedder entry points
   result = Dart_Precompile(standalone_entry_points, NULL, 0);
@@ skipping 369 matching lines @@
   delete mapped_isolate_snapshot_data;
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }