pkg/docgen: removed yaml and append output support

pkg/docgen/bin/docgen.dart

Index: pkg/docgen/bin/docgen.dart
diff --git a/pkg/docgen/bin/docgen.dart b/pkg/docgen/bin/docgen.dart
index 51ba13a6da6769bedb44c83271f8b2def00b7662..16792d3a4c978389d0595a5a1593ff447908a666 100644
--- a/pkg/docgen/bin/docgen.dart
+++ b/pkg/docgen/bin/docgen.dart
@@ -40,11 +40,9 @@ void main(List<String> arguments) {
 
   docgen(files,
       packageRoot: options['package-root'],
-      outputToYaml: !options['json'],
       includePrivate: options['include-private'],
       includeSdk: includeSdk,
       parseSdk: options['parse-sdk'],
-      append: options['append'] && new Directory(options['out']).existsSync(),
       introFileName: introduction,
       out: options['out'],
       excludeLibraries: excludedLibraries,
@@ -103,11 +101,6 @@ ArgParser _initArgParser() {
       callback: (verbose) {
         if (verbose) Logger.root.level = Level.FINEST;
       });
-  parser.addFlag('json', abbr: 'j',
-      help: 'Outputs to JSON. If negated, outputs to YAML. '
-        'If --append is used, it takes the file-format of the previous '
-        'run stated in library_list.json, ignoring the flag.',
-      negatable: true, defaultsTo: true);
   parser.addFlag('include-private',
       help: 'Flag to include private declarations.', negatable: false);
   parser.addFlag('include-sdk',
@@ -119,9 +112,6 @@ ArgParser _initArgParser() {
       defaultsTo: false, negatable: false);
   parser.addOption('package-root',
       help: 'Sets the package root of the library being analyzed.');
-  parser.addFlag('append',
-      help: 'Append to the docs folder, library_list.json and index.txt',
-      defaultsTo: false, negatable: false);
   parser.addFlag('compile', help: 'Clone the documentation viewer repo locally '
       '(if not already present) and compile with dart2js', defaultsTo: false,
       negatable: false);