Fix issues found by analyzer.

tests/standalone/io/string_stream_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:io");
 
 void testUtf8() {
   List<int> data = [0x01,
                     0x7f,
                     0xc2, 0x80,
@@ skipping 260 matching lines @@
 
 class TestException implements Exception {
   TestException();
 }
 
 class ErrorInputStream implements InputStream {
   ErrorInputStream();
   List<int> read([int len]) => null;
   int readInto(List<int> buffer, [int offset, int len]) => 0;
   int available() => 0;
-  void pipe(OutputStream output, [bool close]){ }
+  void pipe(OutputStream output, {bool close: true}){ }
   void close() { }
   bool get closed => true;
   void set onData(void callback()) { }
   void set onClosed(void callback()) { }
   void set onError(void callback(Exception e)) {
     callback(new TestException());
   }
 }
 
 testErrorHandler() {
   var errors = 0;
   var stream = new StringInputStream(new ErrorInputStream());
   stream.onError = (e) {
     errors++;
     Expect.isTrue(e is TestException);
   };
   Expect.equals(1, errors);
 }
 
 main() {
   testUtf8();
   testLatin1();
   testAscii();
   testReadLine1();
   testReadLine2();
   testReadChunks();
   testReadMixed();
   testErrorHandler();
 }