Constructor initializer indent fixes.

pkg/analyzer/lib/src/services/formatter_impl.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.
 
 library formatter_impl;
 
 import 'dart:math';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/parser.dart';
@@ skipping 614 matching lines @@
         token(SEMI_COLON);
         newlines();
         return;
       }
     }
 
     visitPrefixedBody(space, body);
   }
 
   visitConstructorInitializers(ConstructorDeclaration node) {
-    newlines();
+    if (node.initializers.length > 1) {
+      newlines();
+    } else {
+      preserveLeadingNewlines();
+    }
     indent(2);
     token(node.separator /* : */);
     space();
     for (var i = 0; i < node.initializers.length; i++) {
       if (i > 0) {
         // preceding comma
         token(node.initializers[i].beginToken.previous);
         newlines();
         space(n: 2, allowLineLeading: true);
       }
@@ skipping 1058 matching lines @@
     var lastLine =
         lineInfo.getLocation(lastOffset).lineNumber;
     var currentLine =
         lineInfo.getLocation(currentOffset).lineNumber;
     return currentLine - lastLine;
   }
 
   String toString() => writer.toString();
 
 }