Reload is an async operation on WP8 (if it'd be a blocking one, we would end up with a deadlock due to the threading on the platform). The caller doesn't know when we finished working with the stream, therefore we need to dispose the texture stream inside MonoGame.
Merge pull request #2959 from SongArc/wp8_texture2d_reload_disposefix

Fixed stream disposing in Texture2D.Reload on WP8