[glimmer] textarea renders "true" instead of ""

[GavinJoyce]

emberjs/ember.js#14001

The rendered value of textarea is "true" instead of "" when the context value is "".

Given the following controller:

export default Ember.Controller.extend({
  textareaContent1: '',
  textareaContent2: 'some default text',
});

And template:

textareaContent1: {{textarea value=textareaContent1}} <br />
textareaContent2: {{textarea value=textareaContent2}} <br />

htmlbars renders:

glimmer renders: