WebClient.DownloadFileAsync doen't return a Task object (#3293)

Author: fpelliccioni

xml/System.Net/WebClient.xml

@@ -1119,7 +1119,7 @@
         <AssemblyVersion>4.0.0.0</AssemblyVersion>
       </AssemblyInfo>
       <Docs>
-        <summary>Downloads the specified resource to a local file as an asynchronous operation and returns a task object. These methods do not block the calling thread.</summary>
+        <summary>Downloads the specified resource to a local file as an asynchronous operation. These methods do not block the calling thread.</summary>
       </Docs>
     </MemberGroup>
     <Member MemberName="DownloadFileAsync">