Fixes for empty class and method bodies.

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 439 matching lines @@
     visit(node.leftOperand);
     space();
     token(node.operator);
     space();
     visit(node.rightOperand);
   }
 
   visitBlock(Block node) {
     token(node.leftBracket);
     indent();
-    visitNodes(node.statements, precededBy: newlines, separatedBy: newlines);
-    newlines();
+    if (!node.statements.isEmpty) {
+      visitNodes(node.statements, precededBy: newlines, separatedBy: newlines);
+      newlines();
+    } else {
+      preserveLeadingNewlines();
+    }
     token(node.rightBracket, precededBy: unindent);
   }
 
   visitBlockFunctionBody(BlockFunctionBody node) {
     visit(node.block);
   }
 
   visitBooleanLiteral(BooleanLiteral node) {
     token(node.literal);
   }
@@ skipping 48 matching lines @@
     allowContinuedLines((){
       visit(node.typeParameters);
       visitNode(node.extendsClause, precededBy: space);
       visitNode(node.withClause, precededBy: space);
       visitNode(node.implementsClause, precededBy: space);
       visitNode(node.nativeClause, precededBy: space);
       space();
     });
     token(node.leftBracket);
     indent();
-    visitNodes(node.members, precededBy: newlines, separatedBy: newlines);
-    newlines();
+    if (!node.members.isEmpty) {
+      visitNodes(node.members, precededBy: newlines, separatedBy: newlines);
+      newlines();
+    } else {
+      preserveLeadingNewlines();
+    }
     token(node.rightBracket, precededBy: unindent);
   }
 
   visitClassTypeAlias(ClassTypeAlias node) {
     preserveLeadingNewlines();
     visitNodes(node.metadata, followedBy: newlines);
     modifier(node.abstractKeyword);
     token(node.keyword);
     space();
     visit(node.name);
@@ skipping 1154 matching lines @@
     var lastLine =
         lineInfo.getLocation(lastOffset).lineNumber;
     var currentLine =
         lineInfo.getLocation(currentOffset).lineNumber;
     return currentLine - lastLine;
   }
 
   String toString() => writer.toString();
 
 }