Perf: optimized html block names lookup

lib/common/html_blocks.js

@@ -3,8 +3,9 @@
 
 'use strict';
 
+var html_blocks = {};
 
-module.exports = [
+[
   'article',
   'aside',
   'button',
@@ -55,4 +56,7 @@ module.exports = [
   'thead',
   'ul',
   'video'
-];
+].forEach(function (name) { html_blocks[name] = true; });
+
+
+module.exports = html_blocks;

lib/rules_block/htmlblock.js

@@ -48,7 +48,7 @@ module.exports = function htmlblock(state, startLine, endLine, silent) {
       if (!match) { return false; }
     }
     // Make sure tag name is valid
-    if (block_names.indexOf(match[1].toLowerCase()) < 0) { return false; }
+    if (block_names[match[1].toLowerCase()] !== true) { return false; }
     if (silent) { return true; }
 
   } else {