TocFilter: keep using the old punctuation stripping on 1.8.7

The UTF regexp doesn't seem to work correctly under 1.8.7 and causes
existing tests to fail. We don't really care about fixing this case
for 1.8.7 but we don't want the gem to be unusable, so we'll just
special case it for now.

Author: jakedouglas

lib/html/pipeline/toc_filter.rb

@@ -7,11 +7,13 @@ class Pipeline
     # eventually generating the Table of Contents itself, with links
     # to each header
     class TableOfContentsFilter < Filter
+      PUNCTUATION_REGEXP = RUBY_VERSION > "1.9" ? /[^\p{Word}\- ]/u : /[^\w\- ]/
+
       def call
         headers = Hash.new(0)
         doc.css('h1, h2, h3, h4, h5, h6').each do |node|
           name = node.text.downcase
-          name.gsub!(/[^\p{Word}\- ]/u, '') # remove punctuation
+          name.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
           name.gsub!(' ', '-') # replace spaces with dash
 
           uniq = (headers[name] > 0) ? "-#{headers[name]}" : ''

test/html/pipeline/toc_filter_test.rb

@@ -54,5 +54,5 @@ def test_anchors_with_utf8_characters
                  rendered_h1s[0]
     assert_equal "<h1>\n<a name=\"%D0%A0%D1%83%D1%81%D1%81%D0%BA%D0%B8%D0%B9\" class=\"anchor\" href=\"#%D0%A0%D1%83%D1%81%D1%81%D0%BA%D0%B8%D0%B9\"><span class=\"octicon octicon-link\"></span></a>Русский</h1>",
                  rendered_h1s[1]
-  end
+  end if RUBY_VERSION > "1.9" # not sure how to make this work on 1.8.7
 end