Add *.razor file glob to HTML [EASY MERGE] (rouge-ruby#2115)

* Update html.rb

added .razor files to html lexer

* Update html_spec.rb

added razor files to html spec

Author: Inspirateur

lib/rouge/lexers/html.rb

@@ -7,7 +7,7 @@ class HTML < RegexLexer
       title "HTML"
       desc "HTML, the markup language of the web"
       tag 'html'
-      filenames '*.htm', '*.html', '*.xhtml', '*.cshtml'
+      filenames '*.htm', '*.html', '*.xhtml', '*.cshtml', '*.razor'
       mimetypes 'text/html', 'application/xhtml+xml'
 
       def self.detect?(text)

spec/lexers/html_spec.rb

@@ -66,6 +66,7 @@
       assert_guess :filename => 'foo.htm'
       assert_guess :filename => 'foo.xhtml'
       assert_guess :filename => 'foo.cshtml'
+      assert_guess :filename => 'foo.razor'
     end
 
     it 'guesses by mimetype' do