chore(dependencies): switch from es6-shim to core-js (#10884)

modules/@angular/http/src/index.ts

@@ -8,7 +8,7 @@
 
 // Index to be used if Http is ever configured as a standalone npm package.
 // require('reflect-metadata');
-// require('es6-shim');
+// require('core-js');
 // import {HTTP_PROVIDERS, JSONP_PROVIDERS, Http, Jsonp} from './http';
 // import {Injector} from '@angular/core';
 // export * from './http';