Fix handling of 'else if' statement blocks (dartbug.com/17363).

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 906 matching lines @@
       token(node.leftParenthesis);
       visit(node.condition);
       token(node.rightParenthesis);
     });
     space();
     if (hasElse) {
       printAsBlock(node.thenStatement);
       space();
       token(node.elseKeyword);
       space();
-      printAsBlock(node.elseStatement);
+      if (node.elseStatement is IfStatement) {
+        visit(node.elseStatement);
+      } else {
+        printAsBlock(node.elseStatement);
+      }
     } else {
       visit(node.thenStatement);
     }
   }
 
   visitImplementsClause(ImplementsClause node) {
     token(node.keyword);
     space();
     visitCommaSeparatedNodes(node.interfaces);
   }
@@ skipping 811 matching lines @@
     var lastLine =
         lineInfo.getLocation(lastOffset).lineNumber;
     var currentLine =
         lineInfo.getLocation(currentOffset).lineNumber;
     return currentLine - lastLine;
   }
 
   String toString() => writer.toString();
 
 }