Action view shows up when it shouldn't

[scofalik]

When working on ckeditor/ckeditor5-link#169 I noticed that "action view toolbar" is shown when it shouldn't:

1. Select some text, open link toolbar and click cancel.
2. (With ckeditor/ckeditor5-link#169 fix) With a collapsed selection, open link toolbar, then click cancel or save.

I wanted to change _removeFormView method to that:

_removeFormView() {
	if ( this._isFormInPanel ) {
		this._balloon.remove( this.formView );

		if ( !this.editor.editing.model.document.selection.hasAttribute( 'linkHref' ) ) {
			this._hideUI();
		}

		// Because the form has an input which has focus, the focus must be brought back
		// to the editor. Otherwise, it would be lost.
		this.editor.editing.view.focus();
	}
}

I added the long if. Although it worked in manual testing, it caused automatic tests to crash, so maybe there is a better way to achieve that. I didn't want to dig deep into it since I am not that familiar w UI library and concepts.