Fix errors in previous commit

sdk/lib/io/http.dart

Index: sdk/lib/io/http.dart
diff --git a/sdk/lib/io/http.dart b/sdk/lib/io/http.dart
index 972013c192275e2efdb3412c68f1c94f3381533d..a2b063256c7432d0d24074632919642b8a62c4ea 100644
--- a/sdk/lib/io/http.dart
+++ b/sdk/lib/io/http.dart
@@ -977,9 +977,9 @@ abstract class HttpClient {
 
   /**
    * Sets the function to be called when a proxy is requesting
-   * authentication. The proxy used and and the security realm from
-   * the server are passed in the arguments [host], [port] and
-   * [realm].
+   * authentication. Information on the proxy in use and the security
+   * realm for the authentication are passed in the arguments [host],
+   * [port] and [realm].
    *
    * The function returns a [Future] which should complete when the
    * authentication has been resolved. If credentials cannot be