title: What can i use for replacing InMemoryRandomAccessStream in Windows Phone 8?
body: <p>i know there are two classes for IRandomAccessStream interface in WinRT,
  FileRandomAccessStream and InMemoryRandomAccessStream.</p>
  
  <p>now i'm porting one of my apps to wp8 and some of my methods need IRandomAccessStream as return type,but i cannot find InMemoryRandomAccessStream.</p>
  
  <p>how can i create a memorystream and get a IRandomAccessStream from it without InMemoryRandomAccessStream in Windows Phone 8?</p>