Modal component show and hide methods wrong conditional test

[tpra7]

Not a bug, it works perfectly, but not conform to the intention.

The show() method of the Modal component use
if ( this.isHidden ) (always returns true, the method exists)
instead of
if ( this.isHidden() ) or if ( this._isHidden )

Same for the hide() method with :
if ( this.isVisible ) (always returns true, the method exists)
instead of
if ( this.isVisible() ) or if ( ! this._isHidden )