Ensure Haml {} attributes end the contained Ruby

[pilaf]

This fixes an issue with the Haml syntax highlighter where using curly ({}) Haml attributes with a nested Ruby hash literal would get the syntax highlighter trapped in Ruby mode for the rest of the file.

E.g.:

.example{ data: { foo: 'bar' } }
  %p This should be highlighted as Haml

  # This should not be highligted as Ruby!
  class NorShouldThis
    def nope(); end
  end

Before my change it looked like this:

After my change it looks like this:

This is my first time working with vim syntax files, so I'm not sure if I missed anything important, but so far this is working perfectly for me.

[tpope]

I can't reproduce this. Your Ruby syntax highlighting looks different from mine too. nope should be highlighted and () shouldn't be. Do you have a different Ruby highlighter installed?

[pilaf]

@tpope You were right, I was using a different Ruby syntax highlighter (jlcrochet/vim-ruby) and it didn't occur to me that that could be the cause of the issue. Sorry for taking up your time, I'm closing this PR now.