If the focus is on a Menu Button (or Split Menu Button) with a Left Arrow Icon available, pressing the Left Arrow Key should open the menu.

Keyboard Spec under Menu Button (https://wiki.openjdk.java.net/display/OpenJFX/Keyboard+Navigation):
"LEFT Arrow -- If Left Arrow icon is available on the menu button and the menu is not open, open the menu."

In a certain configuration of the HelloButtonMenu sample, the Left Arrow Key will not open a focused Menu Button (or Split Menu Button) that has a Left Arrow Icon showing.

To Reproduce:
0. Run HelloMenuButton sample (java -cp Hello.jar hello.HelloMenuButton)
1. Set Popup Side to Left.
2. Set the RTL checkbox to "checked".
3. Press TAB until focus is on any of the Menu Buttons with a Left Arrow Icon showing.
4. Press the Left Arrow Key. It should open but it doesn't.

If you "uncheck" RTL, the Menu Buttons will show a Right Arrow Icon available. If the focus is set to one of the Menu Buttons now, either a Left or Right Arrow Key will open the menu.

RULE tests/jaws/MenuButtonAndSplitMenuButton any any
RULE tests/narrator/MenuButtonAndSplitMenuButton any any