Focus Mode is not set properly on _ready

[Algorithmus]

Godot version:
3.0.2

OS/device including version:
Arch Linux

Issue description:
ToolButton in a scene has Focus Mode set to None, but when the scene comes up, it still starts up with Focus Mode set to All.

Steps to reproduce:

1. Make a scene and drop a ToolButton in it (presumably this might happen with any other BaseButton).
2. Set the ToolButton Focus Mode to "None".
3. Play the Scene.

You can still programmatically set the focus mode, and that works, but I expect the Focus Mode to be None if I set it to None in the editor.

[guilhermefelipecgs]

Only to complement, when using any node derived from BaseButton the propertie enabled_focus_mode will overwrite focus/mode. If you change the first propertie, the two properties will have the value setted on inspector, otherwise, if you try to change the second, this will not take effect indeed.