Add a snapshot for docgen and use it in the build

utils/compiler/create_snapshot.dart

 // 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.
 
 import 'dart:io';
 
 Future<String> getVersion(var rootPath) {
   var suffix = Platform.operatingSystem == 'windows' ? '.exe' : '';
   var printVersionScript = rootPath.resolve("tools/print_version.py");
   return Process.run("python$suffix",
                      [printVersionScript.toFilePath()]).then((result) {
     if (result.exitCode != 0) {
       throw "Could not generate version";
     }
     return result.stdout.trim();
   });
 }
 
 Future<String> getSnapshotGenerationFile(var args, var rootPath) {
   var dart2js = rootPath.resolve(args["dart2js_main"]);
   var dartdoc = rootPath.resolve(args["dartdoc_main"]);
+  var docgen = rootPath.resolve(args["docgen_main"]);
   return getVersion(rootPath).then((version) {
     var snapshotGenerationText =
 """
 import '${dart2js.toFilePath(windows: false)}' as dart2jsMain;
 import '${dartdoc.toFilePath(windows: false)}' as dartdocMain;
+import '${docgen.toFilePath(windows: false)}' as docgenMain;
 import 'dart:io';
 
 void main(List<String> arguments) {
   if (arguments.length < 1) throw "No tool given as argument";
   String tool = arguments[0];
   if (tool == "dart2js") {
     dart2jsMain.BUILD_ID = "$version";
     dart2jsMain.main(arguments.skip(1).toList());
   } else if (tool == "dartdoc") {
     dartdocMain.main(arguments.skip(1).toList());
+  } else if (tool == "docgen") {
+    docgenMain.main(arguments.skip(1).toList());
   }
 }
 
 """;
     return snapshotGenerationText;
   });
 }
 
 Future<String> getDart2jsSnapshotGenerationFile(var args, var rootPath) {
   var dart2js = rootPath.resolve(args["dart2js_main"]);
@@ skipping 26 matching lines @@
       .then((result) {
         if (result.exitCode != 0) {
           throw "Could not generate snapshot";
         }
       });
 }
 
 /**
  * Takes the following arguments:
  * --output_dir=val     The full path to the output_dir.
  * --dart2js_main=val   The path to the dart2js main script releative to root.

[Bob Nystrom, 2014/01/08 00:16:57]

Update this?

[Alan Knight, 2014/01/08 01:22:52]

Done.

  */
 void main(List<String> arguments) {
   var validArguments = ["--output_dir", "--dart2js_main", "--dartdoc_main",
-                        "--package_root"];
+                        "--docgen_main", "--package_root"];
   var args = {};
   for (var argument in arguments) {
     var argumentSplit = argument.split("=");
     if (argumentSplit.length != 2) throw "Invalid argument $argument, no =";
     if (!validArguments.contains(argumentSplit[0])) {
       throw "Invalid argument $argument";
     }
     args[argumentSplit[0].substring(2)] = argumentSplit[1];
   }
   if (!args.containsKey("dart2js_main")) throw "Please specify dart2js_main";
   if (!args.containsKey("dartdoc_main")) throw "Please specify dartdoc_main";
+  if (!args.containsKey("docgen_main")) throw "Please specify docgen_main";
   if (!args.containsKey("output_dir")) throw "Please specify output_dir";
   if (!args.containsKey("package_root")) throw "Please specify package_root";
 
   var scriptFile = Uri.base.resolveUri(Platform.script);
   var path = scriptFile.resolve(".");
   var rootPath = path.resolve("../..");
   getSnapshotGenerationFile(args, rootPath).then((result) {
     var wrapper = "${args['output_dir']}/utils_wrapper.dart";
     writeSnapshotFile(wrapper, result);
     createSnapshot(wrapper, args["package_root"]);
   });
 
   getDart2jsSnapshotGenerationFile(args, rootPath).then((result) {
     var wrapper = "${args['output_dir']}/dart2js.dart";
     writeSnapshotFile(wrapper, result);
     createSnapshot(wrapper, args["package_root"]);
   });
 
 }