anchor.diff:  
       [<JavaScript>]
       let DrawTriangle () =
  -        let canvas = HTML5.Tags.Canvas []
  +        let canvas = Tags.Canvas []
           match CreateContext canvas with
           | None -> JS.Alert "Couldn't create WebGL context."
           | Some gl ->
  
positive.code: 
      [<JavaScript>]
      let BasicContext () =
          let element = HTML5.Tags.Canvas []
          match CreateContext element with
          | None -> ()
          | Some gl ->
  
negative.code: 
      [<JavaScript>]
      let DrawTunnel () =
          let otherCanvas = Tags.Canvas []
          let canvas = Tags.Canvas []
          match CreateContext canvas with
          | None -> JS.Alert "Couldn't create WebGL context."
          | Some gl ->
  