Avoid maintaining the html escape/unescape regexes independently of the entity maps.

Former-commit-id: 847e58befee7641bc39af37bde12fc99da9edb28

lodash.js

@@ -50,10 +50,6 @@
       reEmptyStringMiddle = /\b(__p \+=) '' \+/g,
       reEmptyStringTrailing = /(__e\(.*?\)|\b__t\)) \+\n'';/g;
 
-  /** Used to match HTML entities and HTML characters */
-  var reEscapedHtml = /&(?:amp|lt|gt|quot|#39);/g,
-      reUnescapedHtml = /[&<>"']/g;
-
   /**
    * Used to match ES6 template delimiters
    * http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.8.6
@@ -1411,6 +1407,10 @@
     /** Used to convert HTML entities to characters */
     var htmlUnescapes = invert(htmlEscapes);
 
+    /** Used to match HTML entities and HTML characters */
+    var reEscapedHtml = RegExp('(' + keys(htmlUnescapes).join('|') + ')', 'g'),
+        reUnescapedHtml = RegExp('[' + keys(htmlEscapes).join('') + ']', 'g');
+
     /*--------------------------------------------------------------------------*/
 
     /**