Add "-i" to command line to specify leading indent.

lib/src/io.dart

 // Copyright (c) 2014, 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.
 
 library dart_style.src.io;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 
@@ skipping 49 matching lines @@
 
   return success;
 }
 
 /// Runs the formatter on [file].
 ///
 /// Returns `true` if successful or `false` if an error occurred.
 bool processFile(FormatterOptions options, File file, {String label}) {
   if (label == null) label = file.path;
 
-  var formatter = new DartFormatter(pageWidth: options.pageWidth);
+  var formatter =
+      new DartFormatter(indent: options.indent, pageWidth: options.pageWidth);
   try {
     var source = new SourceCode(file.readAsStringSync(), uri: file.path);
     options.reporter.beforeFile(file, label);
     var output = formatter.formatSource(source);
     options.reporter
         .afterFile(file, label, output, changed: source.text != output.text);
     return true;
   } on FormatterException catch (err) {
     var color = Platform.operatingSystem != "windows" &&
         stdioType(stderr) == StdioType.TERMINAL;
 
     stderr.writeln(err.message(color: color));
   } catch (err, stack) {
     stderr.writeln('''Hit a bug in the formatter when formatting $label.
 Please report at: github.com/dart-lang/dart_style/issues
 $err
 $stack''');
   }
 
   return false;
 }