not works with 2.8

dropdown-container-content.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNames: ['dropdown-container-content']
});

dropdown-container-trigger.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNames: ['dropdown-container-trigger']
});

dropdown-container.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  showContent: true,
  classNames: ['dropdown-container'],
  position: 'bottom center'
});

dropdown-container.template.hbs

{{yield 
	(
  	hash
    	trigger=(
      	component 'dropdown-container-trigger'
      )
   )
}}

{{#if showContent}}
  {{yield
  	(
    	hash 
      	content=(
        	component 'dropdown-container-content' class=position
        )
    )
	}}
{{/if}}

templates.application.hbs

{{#dropdown-container
	as |dd|
}}
	{{#dd.trigger}}
  	<p>ФЯФЯФЯФ</p>
  {{/dd.trigger}}
  
  {{#dd.content}}
  	1111111
  {{/dd.content}}
{{/dropdown-container}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": true,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.8.1"
  }
}