Fix excess memory usage problem in StringInputStream.

runtime/bin/string_stream.dart

 // Copyright (c) 2011, 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 objects of type T.
 interface _Decoder<T> {
   // 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 10 matching lines @@
   String toString() => "DecoderException: $message";
   final String message;
 }
 
 
 // Utility class for decoding UTF-8 from data delivered as a stream of
 // bytes.
 class _StringDecoderBase implements _Decoder<String> {
   _StringDecoderBase()
       : _bufferList = new _BufferList(),
-        _result = new StringBuffer();
+        _result = new List<int>();
 
   // Add UTF-8 encoded data.
   int write(List<int> buffer) {
     _bufferList.add(buffer);
     // Decode as many bytes into characters as possible.
     while (_bufferList.length > 0) {
       if (!_processNext()) {
         break;
       }
     }
     return buffer.length;
   }
 
   // Check if any characters have been decoded since the last call to decode.
   bool isEmpty() {
     return _result.isEmpty();
   }
 
   // Return the string decoded since the last call to decode.
   String get decoded() {
     if (isEmpty()) {
       return null;
     } else {
-      String result =  _result.toString();
-      _result = new StringBuffer();
+      String result =  new String.fromCharCodes(_result);
+      _result = new List<int>();
       return result;
     }
   }
 
   abstract bool _processNext();
 
   _BufferList _bufferList;
-  StringBuffer _result;
+  List<int> _result;
 }
 
 
 // Utility class for decoding ascii data delivered as a stream of
 // bytes.
 class _AsciiDecoder extends _StringDecoderBase {
   // Process the next ascii encoded character.
   bool _processNext() {
     while (_bufferList.length > 0) {
       int byte = _bufferList.next();
       if (byte > 127) {
         throw new DecoderException("Illegal ASCII character $byte");
       }
-      _result.addCharCode(byte);
+      _result.add(byte);
     }
     return true;
   }
 }
 
 
 // Utility class for decoding Latin-1 data delivered as a stream of
 // bytes.
 class _Latin1Decoder extends _StringDecoderBase {
   // Process the next Latin-1 encoded character.
   bool _processNext() {
     while (_bufferList.length > 0) {
       int byte = _bufferList.next();
-      _result.addCharCode(byte);
+      _result.add(byte);
     }
     return true;
   }
 }
 
 
 // Utility class for decoding UTF-8 from data delivered as a stream of
 // bytes.
 class _UTF8Decoder extends _StringDecoderBase {
   // Process the next UTF-8 encoded character.
@@ skipping 21 matching lines @@
       // Remove the value peeked from the buffer list.
       _bufferList.next();
       for (int i = 0; i < additionalBytes; i++) {
         int byte = _bufferList.next();
         value = value << 6 | (byte & 0x3F);
       }
     } else {
       // Remove the value peeked from the buffer list.
       _bufferList.next();
     }
-    _result.addCharCode(value);
+    _result.add(value);
     return true;
   }
 }
 
 
 class _StringInputStream implements StringInputStream {
   _StringInputStream(InputStream this._input, [String this._encoding]) {
     if (_encoding === null) {
       _encoding = "UTF-8";
     }
@@ skipping 168 matching lines @@
   String _encoding;
   _Decoder _decoder;
   String _buffer;  // String can be buffered here if readLine is used.
   int _bufferLineStart;  // Current offset into _buffer if any.
   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?
   var _clientDataHandler;
   var _clientCloseHandler;
 }