escapeRegExp is no longer used.

underscore.js

@@ -19,9 +19,6 @@
   // Establish the object that gets thrown to break out of a loop iteration.
   var breaker = typeof StopIteration !== 'undefined' ? StopIteration : '__break__';
 
-  // Quick regexp-escaping function, because JS doesn't have a `RegExp.escape()`.
-  var escapeRegExp = function(s) { return s.replace(/([.*+?^${}()|[\]\/\\])/g, '\\$1'); };
-
   // Save bytes in the minified (but not gzipped) version:
   var ArrayProto = Array.prototype, ObjProto = Object.prototype;