Correctly handle optional length in HTTP output stream writeFrom

sdk/lib/io/http_impl.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.
 
 // The close queue handles graceful closing of HTTP connections. When
 // a connection is added to the queue it will enter a wait state
 // waiting for all data written and possibly socket shutdown from
 // peer.
 class _CloseQueue {
   _CloseQueue() : _q = new Set<_HttpConnectionBase>();
@@ skipping 665 matching lines @@
 
 
 class _HttpOutputStream extends _BaseOutputStream implements OutputStream {
   _HttpOutputStream(_HttpRequestResponseBase this._requestOrResponse);
 
   bool write(List<int> buffer, [bool copyBuffer = true]) {
     return _requestOrResponse._streamWrite(buffer, copyBuffer);
   }
 
   bool writeFrom(List<int> buffer, [int offset = 0, int len]) {
+    if (offset < 0 || offset >= buffer.length) throw new ArgumentError();
+    len = len != null ? len : buffer.length - offset;
+    if (len < 0) throw new ArgumentError();
     return _requestOrResponse._streamWriteFrom(buffer, offset, len);
   }
 
   void flush() {
     _requestOrResponse._streamFlush();
   }
 
   void close() {
     _requestOrResponse._streamClose();
   }
@@ skipping 1454 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }