remove docgen source and targets from build

utils/compiler/create_snapshot.dart

Index: utils/compiler/create_snapshot.dart
diff --git a/utils/compiler/create_snapshot.dart b/utils/compiler/create_snapshot.dart
index 01237921b9d1abcea5979ff83e6206318cd928fa..1a274310cb5909458e38be3809e2fce9dec9adf6 100644
--- a/utils/compiler/create_snapshot.dart
+++ b/utils/compiler/create_snapshot.dart
@@ -18,12 +18,10 @@ Future<String> getVersion(var rootPath) {
 
 Future<String> getSnapshotGenerationFile(var args, var rootPath) {
   var dart2js = rootPath.resolve(args["dart2js_main"]);
-  var docgen = rootPath.resolve(args["docgen_main"]);
   return getVersion(rootPath).then((version) {
     var snapshotGenerationText =
 """
 import '${dart2js.toFilePath(windows: false)}' as dart2jsMain;
-import '${docgen.toFilePath(windows: false)}' as docgenMain;
 import 'dart:io';
 
 void main(List<String> arguments) {
@@ -32,8 +30,6 @@ void main(List<String> arguments) {
   if (tool == "dart2js") {
     dart2jsMain.BUILD_ID = "$version";
     dart2jsMain.main(arguments.skip(1).toList());
-  } else if (tool == "docgen") {
-    docgenMain.main(arguments.skip(1).toList());
   }
 }
 
@@ -84,12 +80,11 @@ Future createSnapshot(var dart_file, var packageRoot) {
  * Takes the following arguments:
  * --output_dir=val     The full path to the output_dir.
  * --dart2js_main=val   The path to the dart2js main script relative to root.
- * --docgen_main=val    The path to the docgen main script relative to root.
  * --package-root=val   The package-root used to find packages for the snapshot.
  */
 void main(List<String> arguments) {
   var validArguments = ["--output_dir", "--dart2js_main",
-                        "--docgen_main", "--package_root"];
+                        "--package_root"];
   var args = {};
   for (var argument in arguments) {
     var argumentSplit = argument.split("=");
@@ -100,7 +95,6 @@ void main(List<String> arguments) {
     args[argumentSplit[0].substring(2)] = argumentSplit[1];
   }
   if (!args.containsKey("dart2js_main")) throw "Please specify dart2js_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";