Replace Haml with Hamlit.

Hamlit is a library that's faster than Haml while implementing most of its features: https://github.com/k0kubun/hamlit

Not sure if this breaks anything, but as far as I can tell most things work the same. No obvious regressions that I've been able to find.

Gemfile

@@ -76,7 +76,7 @@ gem 'rack-cors',    '~> 0.4.0', require: 'rack/cors'
 gem "kaminari", "~> 0.17.0"
 # HAML
-gem "haml-rails", '~> 0.9.0'
+gem "hamlit"
 # Files attachments
 gem "carrierwave", '~> 0.10.0'
@@ -344,5 +344,6 @@ gem 'oauth2', '~> 1.0.0'
 # Soft deletion
 gem "paranoia", "~> 2.0"
+
 # Health check
 gem 'health_check', '~> 1.5.1'

Gemfile.lock

@@ -320,14 +320,10 @@ GEM
     grape-entity (0.4.8)
       activesupport
       multi_json (>= 1.3.2)
-    haml (4.0.7)
+    hamlit (2.5.0)
+      temple (~> 0.7.6)
+      thor
       tilt
-    haml-rails (0.9.0)
-      actionpack (>= 4.0.1)
-      activesupport (>= 4.0.1)
-      haml (>= 4.0.6, < 5.0)
-      html2haml (>= 1.0.1)
-      railties (>= 4.0.1)
     hashie (3.4.3)
     health_check (1.5.1)
       rails (>= 2.3.0)
@@ -337,11 +333,6 @@ GEM
     html-pipeline (1.11.0)
       activesupport (>= 2)
       nokogiri (~> 1.4)
-    html2haml (2.0.0)
-      erubis (~> 2.7.0)
-      haml (~> 4.0.0)
-      nokogiri (~> 1.6.0)
-      ruby_parser (~> 3.5)
     htmlentities (4.3.4)
     http_parser.rb (0.5.3)
     httparty (0.13.7)
@@ -733,6 +724,7 @@ GEM
       railties (>= 3.2.5, < 6)
     teaspoon-jasmine (2.2.0)
       teaspoon (>= 1.0.0)
+    temple (0.7.7)
     term-ansicolor (1.3.2)
       tins (~> 1.0)
     test_after_commit (0.4.2)
@@ -882,7 +874,7 @@ DEPENDENCIES
   gon (~> 6.0.1)
   grape (~> 0.13.0)
   grape-entity (~> 0.4.2)
-  haml-rails (~> 0.9.0)
+  hamlit
   health_check (~> 1.5.1)
   hipchat (~> 1.5.0)
   html-pipeline (~> 1.11.0)

app/helpers/application_helper.rb

@@ -197,7 +197,7 @@ module ApplicationHelper
   def render_markup(file_name, file_content)
     if gitlab_markdown?(file_name)
-      Haml::Helpers.preserve(markdown(file_content))
+      Hamlit::RailsHelpers.preserve(markdown(file_content))
     elsif asciidoc?(file_name)
       asciidoc(file_content)
     elsif plain?(file_name)

config/initializers/haml.rb

-Haml::Template.options[:ugly] = true
-
-# Remove the `:coffee` and `:coffeescript` filters
-#
-# See https://git.io/vztMu and http://stackoverflow.com/a/17571242/223897
-Haml::Filters.remove_filter('coffee')
-Haml::Filters.remove_filter('coffeescript')

config/initializers/hamlit.rb

+module Hamlit
+  class TemplateHandler
+    def call(template)
+      Engine.new(
+        generator: Temple::Generators::RailsOutputBuffer,
+        attr_quote: '"',
+      ).call(template.source)
+    end
+  end
+end
+
+ActionView::Template.register_template_handler(
+  :haml,
+  Hamlit::TemplateHandler.new,
+)