Chore: Remove es6-map and es6-weakmap as they are included in node4

package.json

@@ -23,8 +23,6 @@
     "betarelease": "eslint-prerelease beta"
   },
   "dependencies": {
-    "es6-map": "^0.1.3",
-    "es6-weak-map": "^2.0.1",
     "esrecurse": "^4.1.0",
     "estraverse": "^4.1.1"
   },

src/scope-manager.js

@@ -23,7 +23,6 @@
 */
 "use strict";
 
-const WeakMap = require('es6-weak-map');
 const Scope = require('./scope');
 const assert = require('assert');
 

src/scope.js

@@ -24,7 +24,6 @@
 "use strict";
 
 const Syntax = require('estraverse').Syntax;
-const Map = require('es6-map');
 
 const Reference = require('./reference');
 const Variable = require('./variable');