dart2dart fix synthesized constructor appearing in unparser. Don't output it.

tests/compiler/dart2js/unparser_test.dart

 // Copyright (c) 2012, 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:uri');
 #import('parser_helper.dart');
 #import("../../../lib/compiler/compiler.dart");
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 
 testUnparse(String statement) {
@@ skipping 14 matching lines @@
 interface int extends num {}
 interface double extends num {}
 interface String {}
 interface Function {}
 interface List {}
 interface Closure {}
 interface Dynamic {}
 interface Null {}
 ''';
 
-testDart2Dart(String src, void continuation(String s)) {
+testDart2Dart(String src, [void continuation(String s)]) {
   fileUri(path) => new Uri(scheme: 'file', path: path);
 
   final scriptUri = fileUri('script.dart');
 
   provider(uri) {
     if (uri == scriptUri) return new Future.immediate(src);
     if (uri.path.endsWith('/core.dart')) return new Future.immediate(coreLib);
     return new Future.immediate('');
   }
 
   handler(uri, begin, end, message, kind) {
     if (kind === Diagnostic.ERROR || kind === Diagnostic.CRASH) {
       Expect.fail('$uri: $begin-$end: $message [$kind]');
     }
   }
 
+  // If continuation is not provided, check that source string remains the same.
+  if (continuation == null) {
+    continuation = (s) => Expect.equals(src, s);
+  }
   compile(
       scriptUri,
       fileUri('libraryRoot'),
       fileUri('packageRoot'),
       provider,
       handler,
       const ['--output-type=dart', '--unparse-validation']).then(continuation);
 }
 
 testGenericTypes() {
@@ skipping 50 matching lines @@
 main() {
   should_be_kept();
 }
 ''';
   testDart2Dart(src, (String s) {
     Expect.equals('should_be_kept(){}main(){should_be_kept();}', s);
   });
 }
 
 testTopLevelField() {
-  final src = 'final String x="asd";main(){x;}';
-  testDart2Dart(src, (String s) => Expect.equals(src, s));
+  testDart2Dart('final String x="asd";main(){x;}');
 }
 
 testSimpleObjectInstantiation() {
   testUnparse('main(){new Object();}');
 }
 
 testSimpleTopLevelClass() {
-  final src = 'main(){new A();}class A{A(){}}';
-  testDart2Dart(src, (String s) => Expect.equals(src, s));
+  testDart2Dart('main(){new A();}class A{A(){}}');
+}
+
+testClassWithSynthesizedConstructor() {
+  testDart2Dart('main(){new A();}class A{}');
+}
+
+testClassWithMethod() {
+  testDart2Dart('main(){var a=new A(); a.foo();}class A{void foo(){}}');
 }
 
 main() {
   testGenericTypes();
   testForLoop();
   testEmptyList();
   testClosure();
   testIndexedOperatorDecl();
   testNativeMethods();
   testPrefixIncrements();
   testConstModifier();
   testSimpleFileUnparse();
   testSimpleObjectInstantiation();
   testSimpleTopLevelClass();
+  testClassWithSynthesizedConstructor();
+  testClassWithMethod();
   testTopLevelField();
 }