Updated the deprecation for `ember-htmlbars.ember-handlebars-safestring` to made mention of `Ember.String.isHtmlSafe` and the related polyfill.
Updated the deprecation for `ember-htmlbars.ember-handlebars-safestring` to made mention of `Ember.String.isHtmlSafe` and the related polyfill.

AaronSikes/website,SaladFork/emberjs-website,SaladFork/emberjs-website,josemarluedke/ember-website,workmanw/ember-website,workmanw/ember-website,bmac/website,workmanw/ember-website,josemarluedke/ember-website,kpfefferle/website,bmac/website,josemarluedke/ember-website,kpfefferle/website,AaronSikes/website,bmac/website,kpfefferle/website,workmanw/ember-website,SaladFork/emberjs-website,josemarluedke/ember-website,AaronSikes/website,bmac/website,SaladFork/emberjs-website