Incorrect Highlighting For Multiple Line Type Signatures

Thanks for awesome plugin!

I wrote haskell codes such as:

``` haskell
dbPageWrapper :: (DashBoardPage p, Monad m) =>
  T.Text -> p -> HtmlT m a -> HtmlT m b -> HtmlT m b -- disable type highlighting
dbPageWrapper pref page headerC mainC = do
  ...
```

Then, I noticed missing syntax.

I use GHC 7.10.3.  Probably, because building is passed, this is legal syntax.
