Windows Store Compile Error: Dictionary instead of Hashtable?

Foreword: I have already searched the Unity forums as well as here, but if I missed something please let me know.

I’m porting our existing Unity game (currently on iOS, Android, and Facebook) to the Windows Store platform. I’ve gone through the links listed here and have made tiny baby steps towards a build-able game, and I expect more issues later down the road, but I’ve already hit my first roadblock.

Now, when I switch my platform to Windows Store, I get this error:

error CS1502: The best overloaded method match for `UnityEngine.WWW.WWW(string, byte[], System.Collections.Generic.Dictionary<string,string>)' has some invalid arguments
error CS1503: Argument `#3' cannot convert `System.Collections.Hashtable' expression to type `System.Collections.Generic.Dictionary<string,string>'

The documentation on WWW says that third parameter is a System.Collections.Hashtable. For some reason when targeting Windows Store, Unity thinks that WWW takes a Dictionary<string, string> instead. I am aware that Windows Store apps use a different version of .NET that doesn’t define Hashtables, and I’m using the new definitions written by Jodon Karlik’s in his example project here. However all of that is wrapped in a #if UNITY_WINRT && !UNITY_EDITOR, so it should only take effect while building or on device.

I have a feeling it’s something to do with what version of .NET being used. My Compilation Override is set to None, so by my understanding the editor should still be using Mono.

From my search, it seems that my issue is unique. Any help at all, if it’s something obvious I missed or it’s something ridiculously obscure and undocumented, would be helpful!

I found a workaround that serves my purposes, at least for the time being - I am still only at the beginning of the port process, so we’ll see.

In the spirit of perchik’s advice, I simply wrote a function to convert a Hashtable to a Dictionary so WWW would shut up. Fortunately we weren’t using it in too many places, so it wasn’t as big a deal as I was dreading.