Remove useless CreateFromStdIcon() from wxMSW art provider

This function has become completely trivial after the previous commit,
so just remove it and create the bitmap from the icon directly in
CreateBitmap().

src/msw/artmsw.cpp

@@ -203,16 +203,6 @@ protected:
                                   const wxSize& size) wxOVERRIDE;
 };
 
-static wxBitmap CreateFromStdIcon(const char *iconName,
-                                  const wxArtClient& client)
-{
-    wxIcon icon(iconName);
-    wxBitmap bmp;
-    bmp.CopyFromIcon(icon);
-
-    return bmp;
-}
-
 wxBitmap wxWindowsArtProvider::CreateBitmap(const wxArtID& id,
                                             const wxArtClient& client,
                                             const wxSize& size)
@@ -284,7 +274,7 @@ wxBitmap wxWindowsArtProvider::CreateBitmap(const wxArtID& id,
             name = "wxICON_QUESTION";
 
         if ( name )
-            return CreateFromStdIcon(name, client);
+            return wxIcon(name);
     }
 
     // for anything else, fall back to generic provider: