Add HTTP/1.0 support and simplify persistent connections handling

runtime/bin/http.dart

Index: runtime/bin/http.dart
diff --git a/runtime/bin/http.dart b/runtime/bin/http.dart
index f275a93e7c4611edff2dea64703637be3d3167e5..e687ec9df40580c6a57e953db54e029d6678e938 100644
--- a/runtime/bin/http.dart
+++ b/runtime/bin/http.dart
@@ -110,11 +110,6 @@ interface HttpRequest default _HttpRequest {
   int get contentLength();
 
   /**
-   * Returns the keep alive state of the connection.
-   */
-  bool get keepAlive();
-
-  /**
    * Returns the method for the request.
    */
   String get method();
@@ -164,13 +159,6 @@ interface HttpResponse default _HttpResponse {
   int contentLength;
 
   /**
-   * Gets and sets the keep alive state of the connection. If the
-   * associated request have a keep alive state of false setting keep
-   * alive to true will have no effect.
-   */
-  bool keepAlive;
-
-  /**
    * Gets and sets the status code. Any integer value is accepted, but
    * for the official HTTP status codes use the fields from
    * [HttpStatus].
@@ -315,11 +303,6 @@ interface HttpClientRequest default _HttpClientRequest {
   int contentLength;
 
   /**
-   * Gets and sets the keep alive state of the connection.
-   */
-  bool keepAlive;
-
-  /**
    * Gets and sets the " host part of the "Host" header for the
    * connection. By default this will be set to the value of the host
    * used when initiating the connection.
@@ -379,11 +362,6 @@ interface HttpClientResponse default _HttpClientResponse {
   int get contentLength();
 
   /**
-   * Returns the keep alive state of the connection.
-   */
-  bool get keepAlive();
-
-  /**
    * Returns the date value for the "Expires" header. Returns null if
    * the response has no "Expires" header. Throws a HttpException if
    * the response has an "Expires" header which is not formatted as a