Improve the handling of the connection header

runtime/bin/http_impl.dart

Index: runtime/bin/http_impl.dart
diff --git a/runtime/bin/http_impl.dart b/runtime/bin/http_impl.dart
index e8e5ff14bf0c59d36a626089939a763f320d03c0..dcab3ca3b9d8088d20aec47b38aba7172df8098d 100644
--- a/runtime/bin/http_impl.dart
+++ b/runtime/bin/http_impl.dart
@@ -208,7 +208,7 @@ class _HttpHeaders implements HttpHeaders {
       sb.add(": ");
       for (int i = 0; i < values.length; i++) {
         if (i > 0) {
-          sb.add(": ");
+          sb.add(", ");
         }
         sb.add(values[i]);
       }
@@ -237,6 +237,7 @@ class _HttpRequestResponseBase {
   }
 
   int get contentLength() => _contentLength;
+  bool get persistentConnection() => _persistentConnection;
   HttpHeaders get headers() => _headers;
 
   bool _write(List<int> data, bool copyBuffer) {
@@ -347,6 +348,8 @@ class _HttpRequestResponseBase {
   // including headers or chunk information of using chinked transfer
   // encoding.
   int _bodyBytesWritten = 0;
+
+  bool _persistentConnection = true;
 }
 
 
@@ -459,6 +462,11 @@ class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
     _reasonPhrase = reasonPhrase;
   }
 
+  void set persistentConnection(bool persistentConnection) {
+    if (_outputStream != null) throw new HttpException("Header already sent");
+    _persistentConnection = persistentConnection;
+  }
+
   OutputStream get outputStream() {
     if (_state >= DONE) throw new HttpException("Response closed");
     if (_outputStream == null) {
@@ -594,16 +602,16 @@ class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
 
     // Determine the value of the "Connection" header.
     if (_protocolVersion == "1.1" && !_persistentConnection) {
-      _headers.set("Connection", "close");
+      _headers.add(HttpHeaders.CONNECTION, "close");
     } else if (_protocolVersion == "1.0" && _persistentConnection) {
-      _headers.set("Connection", "keep-alive");
+      _headers.add(HttpHeaders.CONNECTION, "keep-alive");
     }
     // Determine the value of the "Transfer-Encoding" header based on
     // whether the content length is known.
     if (_contentLength > 0) {
-      _headers.set("Content-Length", _contentLength.toString());
+      _headers.set(HttpHeaders.CONTENT_LENGTH, _contentLength.toString());
     } else {
-      _headers.set("Transfer-Encoding", "chunked");
+      _headers.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
     }
 
     // Write headers.
@@ -616,7 +624,6 @@ class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
   int _statusCode;
   String _reasonPhrase;
   String _protocolVersion;
-  bool _persistentConnection;
   _HttpOutputStream _outputStream;
   Function _streamErrorHandler;
 }
@@ -871,6 +878,7 @@ class _HttpConnection extends _HttpConnectionBase {
 
   void _onHeadersComplete() {
     _request._onHeadersComplete();
+    _request._persistentConnection = _httpParser.persistentConnection;
     _response._persistentConnection = _httpParser.persistentConnection;
     if (onRequestReceived != null) {
       onRequestReceived(_request, _response);
@@ -1035,6 +1043,11 @@ class _HttpClientRequest
     _contentLength = contentLength;
   }
 
+  void set persistentConnection(bool persistentConnection) {
+    if (_state >= HEADER_SENT) throw new HttpException("Header already sent");
+    _persistentConnection = persistentConnection;
+  }
+
   OutputStream get outputStream() {
     if (_state == DONE) throw new HttpException("Request closed");
     if (_outputStream == null) {
@@ -1090,13 +1103,17 @@ class _HttpClientRequest
     _httpConnection._write(_Const.HTTP11);
     _writeCRLF();
 
+    // Determine the value of the "Connection" header.
+    if (!_persistentConnection) {
+      _headers.add(HttpHeaders.CONNECTION, "close");
+    }
     // Determine the value of the "Transfer-Encoding" header based on
     // whether the content length is known. If there is no content
     // neither "Content-Length" nor "Transfer-Encoding" is set
     if (_contentLength > 0) {
-      _headers.set("Content-Length", _contentLength.toString());
+      _headers.set(HttpHeaders.CONTENT_LENGTH, _contentLength.toString());
     } else if (_contentLength < 0) {
-      _headers.set("Transfer-Encoding", "chunked");
+      _headers.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
     }
 
     // Write headers.
@@ -1266,6 +1283,7 @@ class _HttpClientConnection
   }
 
   void _onHeadersComplete() {
+    _response._persistentConnection = _httpParser.persistentConnection;
     _response._onHeadersComplete();
   }