Reland: Add more API fuzzing and fix the issues encountered.

runtime/bin/string_stream.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.
 
 // Interface for decoders decoding binary data into string data. The
 // decoder keeps track of line breaks during decoding.
 interface _StringDecoder {
   // Add more binary data to be decoded. The ownership of the buffer
   // is transfered to the decoder and the caller most not modify it any more.
   int write(List<int> buffer);
@@ skipping 19 matching lines @@
 
 class _StringDecoders {
   static _StringDecoder decoder(Encoding encoding) {
     if (encoding == Encoding.UTF_8) {
       return new _UTF8Decoder();
     } else if (encoding == Encoding.ISO_8859_1) {
       return new _Latin1Decoder();
     } else if (encoding == Encoding.ASCII) {
       return new _AsciiDecoder();
     } else {
-      throw new StreamException("Unsupported encoding ${encoding.name}");
+      if (encoding is Encoding) {
+        throw new StreamException("Unsupported encoding ${encoding.name}");
+      } else {
+        throw new StreamException("Unsupported encoding ${encoding}");
+      }
     }
   }
 }
 
 
 class DecoderException implements Exception {
   const DecoderException([String this.message]);
   String toString() => "DecoderException: $message";
   final String message;
 }
@@ skipping 459 matching lines @@
   bool _inputClosed = false;  // Is the underlying input stream closed?
   bool _closed = false;  // Is this stream closed.
   bool _eof = false;  // Has all data been read from the decoder?
   Timer _scheduledDataCallback;
   Timer _scheduledLineCallback;
   Timer _scheduledCloseCallback;
   Function _clientDataHandler;
   Function _clientLineHandler;
   Function _clientCloseHandler;
 }