Add CommonJS file glob to JavaScript lexer (#1511)

This commit adds the `*.cljs` fille glob to the JavaScript lexer.
Node.js treats files ending in the `.cjs` extension as CommonJS modules.

Co-authored-by: Michael Camilleri <mike@inqk.net>

lib/rouge/lexers/javascript.rb

@@ -15,7 +15,7 @@ class Javascript < RegexLexer
 
       tag 'javascript'
       aliases 'js'
-      filenames '*.js', '*.mjs'
+      filenames '*.cjs', '*.js', '*.mjs'
       mimetypes 'application/javascript', 'application/x-javascript',
                 'text/javascript', 'text/x-javascript'
 

spec/lexers/javascript_spec.rb

@@ -17,7 +17,9 @@
     include Support::Guessing
 
     it 'guesses by filename' do
+      assert_guess :filename => 'foo.cjs'
       assert_guess :filename => 'foo.js'
+      assert_guess :filename => 'foo.mjs'
     end
 
     it 'guesses by mimetype' do