cookie: Adding better subdomain support
cookie: Adding better subdomain support

We used to just use the default domain for whatever page the user was
on. This fix will tie users across subdomains for sites which use
both multiple subdomains (e.g. www., blog., etc).

graingert/analytics.js,astronomerio/analytics.js,okgrow/analytics.js,MunGell/analytics.js,nice-fungal/analytics.js-core,Scratch-it/analytics.js,st3w4r/analytics.js,segmentio/analytics.js-core,segmentio/analytics.js-core,segmentio/analytics.js,attribution/analytics.js,abulrim/analytics.js,nice-fungal/analytics.js-core,segmentio/analytics.js-core,Resly/www-analytics.js