Ember 2.10.0 #14704 workaround

components.test-one.js

import Ember from 'ember';

const {
	String: { htmlSafe }
} = Ember;

export default Ember.Component.extend({
  attributeBindings: 'style'.w(),
  style: '',
  
  getStyle(propName) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    console.log('123', style);
    return style.match(regexp);
  },
  setStyle(propName, value) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    if (regexp.test(style)) {
      console.log('1', style);
    	this.set('style', htmlSafe(style.replace(regexp, `${propName}:${value};`)));
      console.log('12', this.get('style'));
    } else {
      console.log('2', style);
    	this.set('style', Ember.String.htmlSafe(`${style}${propName}:${value};`));
      console.log('22', this.get('style'));
    }
    return value;
  },
  
  init() {
    this._super(...arguments);
    this.set('style', htmlSafe(this.get('style')));
    Ember.run.later(this, () => {
      this.set('isVisible', true);
    }, 5000);
  },
  didInsertElement() {
    this._super(...arguments);
  	this.setStyle('color', 'blue');
  }
});

components.test-three.js

import Ember from 'ember';

const {
	String: { htmlSafe }
} = Ember;

export default Ember.Component.extend({
  isVisible: false,
  attributeBindings: 'style'.w(),
  style: '',
  
  getStyle(propName) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    console.log('123', style);
    return style.match(regexp);
  },
  setStyle(propName, value) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    if (regexp.test(style)) {
      console.log('1', style);
    	this.set('style', htmlSafe(style.replace(regexp, `${propName}:${value};`)));
      console.log('12', this.get('style'));
    } else {
      console.log('2', style);
    	this.set('style', Ember.String.htmlSafe(`${style}${propName}:${value};`));
      console.log('22', this.get('style'));
    }
    return value;
  },
  
  init() {
    this._super(...arguments);
    this.set('style', htmlSafe(this.get('style')));
    Ember.run.later(this, () => {
      this.set('isVisible', true);
    }, 5000);
  },
  didInsertElement() {
    this._super(...arguments);
  	this.setStyle('color', 'red');
  }
});

components.test-two.js

import Ember from 'ember';

const {
	String: { htmlSafe }
} = Ember;

export default Ember.Component.extend({
  attributeBindings: 'style'.w(),
  style: '',
  
  getStyle(propName) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    console.log('123', style);
    return style.match(regexp);
  },
  setStyle(propName, value) {
  	let style = this.get('style.string'),
        regexp = new RegExp(`${propName}\\:[\\w\\s\\d]*\\;`, 'ig');
    if (regexp.test(style)) {
      console.log('1', style);
    	this.set('style', htmlSafe(style.replace(regexp, `${propName}:${value};`)));
      console.log('12', this.get('style'));
    } else {
      console.log('2', style);
    	this.set('style', Ember.String.htmlSafe(`${style}${propName}:${value};`));
      console.log('22', this.get('style'));
    }
    return value;
  },
  
  init() {
    this._super(...arguments);
    this.set('style', htmlSafe(this.get('style')));
    Ember.run.later(this, () => {
      this.set('isVisible', false);
    }, 5000);
    Ember.run.later(this, () => {
      this.set('isVisible', true);
    }, 10000);
  },
  didInsertElement() {
    this._super(...arguments);
  	this.setStyle('color', 'red');
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  textAreaVisible: true,
  actions: {
  	toggleVisibilityTextArea() {
    	this.toggleProperty('textAreaVisible');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

<div>{{test-one}}</div>
<div>{{test-two}}</div>
<div>{{test-three}}</div>
<div>{{textarea isVisible=textAreaVisible}}</div>
<button type='button' {{action 'toggleVisibilityTextArea'}}> Toggle visibility TextArea</button>

templates.components.test-one.hbs

It's work fine.

templates.components.test-three.hbs

It's broken.

templates.components.test-two.hbs

It's broken after hiding.

tests.helpers.destroy-app.js

import Ember from 'ember';

export default function destroyApp(application) {
  Ember.run(application, 'destroy');
}

tests.helpers.resolver.js

import Resolver from '../../resolver';
import config from '../../config/environment';

const resolver = Resolver.create();

resolver.namespace = {
  modulePrefix: config.modulePrefix,
  podModulePrefix: config.podModulePrefix
};

export default resolver;

tests.helpers.start-app.js

import Ember from 'ember';
import Application from '../../app';
import config from '../../config/environment';

const { run } = Ember;
const assign = Ember.assign || Ember.merge;

export default function startApp(attrs) {
  let application;

  let attributes = assign({rootElement: "#test-root"}, config.APP);
  attributes = assign(attributes, attrs); // use defaults, but you can override;

  run(() => {
    application = Application.create(attributes);
    application.setupForTesting();
    application.injectTestHelpers();
  });

  return application;
}

tests.test-helper.js

import resolver from './helpers/resolver';
import {
  setResolver
} from 'ember-qunit';

setResolver(resolver);

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "release",
    "ember-data": "2.9.0",
    "ember-template-compiler": "release",
    "ember-testing": "release"
  },
  "addons": {}
}