Avoid printing braces for one-statement blocks in js-printer.

tests/compiler/dart2js/js_parser_statements_test.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.
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'mock_compiler.dart';
 import 'package:compiler/src/js/js.dart' as jsAst;
 import 'package:compiler/src/js/js.dart' show js;
@@ skipping 305 matching lines @@
     // Use the same name several times.
     testStatement('#a.prototype.#a = function(#b) { return #c.#c };',
                   {'a': 'name1_2',
                    'b': ['r', 'y'],
                    'c': 'name4_5'},
                   'name1_2.prototype.name1_2 = function(r, y) {\n'
                   '  return name4_5.name4_5;\n'
                   '};'),
 
     testStatement('label: while (a) { label2: break label;}', [],
-        'label:\n  while (a) {\n    label2:\n      break label;\n  }'),
+        'label:\n  while (a)\n    label2:\n      break label;\n  '),
 
 
     testStatement('var # = 3', ['x'], 'var x = 3;'),
     testStatement('var # = 3',
                   [new jsAst.VariableDeclaration('x')],
                   'var x = 3;'),
     testStatement('var # = 3, # = #',
                   ['x', 'y', js.number(2)],
                   'var x = 3, y = 2;'),
     testStatement('var #a = 3, #b = #c',
         {"a": 'x', "b": 'y', "c": js.number(2)},
                   'var x = 3, y = 2;'),
     testStatement('function #() {}', ['x'], 'function x() {\n}'),
     testStatement('function #() {}',
                   [new jsAst.VariableDeclaration('x')],
                   'function x() {\n}'),
     testStatement('try {} catch (#) {}', ['x'], 'try {\n} catch (x) {\n}'),
     testStatement('try {} catch (#a) {}', {"a": 'x'}, 'try {\n} catch (x) {\n}'),
     testStatement('try {} catch (#a) {}',
                   {"a": new jsAst.VariableDeclaration('x')},
                   'try {\n} catch (x) {\n}'),
   ]));
 }