Render string for slim template

Author: rsludge

autoload/rails.vim

@@ -3346,7 +3346,7 @@ function! s:Extract(bang,...) range abort
     let renderstr = "xml << ".s:sub(renderstr,"render ","render(").")"
   elseif ext == "rjs"
     let renderstr = "page << ".s:sub(renderstr,"render ","render(").")"
-  elseif ext == "haml"
+  elseif ext == "haml" || ext == "slim"
     let renderstr = "= ".renderstr
   elseif ext == "mn"
     let renderstr = "_".renderstr