Remove harmony-collections shim in Gruntfile

eslint cannot load if this shim is present.

build/Gruntfile.coffee

@@ -13,10 +13,6 @@ _ = require 'underscore-plus'
 
 packageJson = require '../package.json'
 
-# Shim harmony collections in case grunt was invoked without harmony
-# collections enabled
-_.extend(global, require('harmony-collections')) unless global.WeakMap?
-
 module.exports = (grunt) ->
   grunt.loadNpmTasks('grunt-babel')
   grunt.loadNpmTasks('grunt-coffeelint')

build/package.json

@@ -27,7 +27,6 @@
     "grunt-peg": "~1.1.0",
     "grunt-shell": "~0.3.1",
     "grunt-standard": "^1.0.2",
-    "harmony-collections": "~0.3.8",
     "legal-eagle": "~0.10.0",
     "minidump": "~0.9",
     "npm": "2.13.3",