Do error propagation for decoder errors in string stream.

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");
+#import("dart:isolate");
 
 void testUtf8() {
   List<int> data = [0x01,
                     0x7f,
                     0xc2, 0x80,
                     0xdf, 0xbf,
                     0xe0, 0xa0, 0x80,
                     0xef, 0xbf, 0xbf];
   ListInputStream s = new ListInputStream();
   s.write(data);
@@ skipping 275 matching lines @@
 testErrorHandler() {
   var errors = 0;
   var stream = new StringInputStream(new ErrorInputStream());
   stream.onError = (e) {
     errors++;
     Expect.isTrue(e is TestException);
   };
   Expect.equals(1, errors);
 }
 
+testEncodingErrorWithHandler() {
+  var port = new ReceivePort();    
+  var errors = 0;
+  var expected = [206, 187, 120, 46, 32, 120, 10];
+  ListInputStream input = new ListInputStream();
+  input.write(expected);
+  var stringStream = new StringInputStream(input, Encoding.ASCII);
+  stringStream.onData = () {
+    Expect.fail("We should not get any data");
+  };
+  stringStream.onError = (e) {
+    port.close();
+    Expect.isTrue(e is Exception);
+  };
+}
+
+
 main() {
   testUtf8();
   testLatin1();
   testAscii();
   testReadLine1();
   testReadLine2();
   testReadChunks();
   testReadMixed();
   testErrorHandler();
+  testEncodingErrorWithHandler();
 }