Change order of setting isOpen

Because the WindowManager.addView() method can indirectly call
PhoneWindow.closePanel() it is critical to set isOpen after the
addView call returns in PhoneWindow.openPanel. Otherwise when
closePanel sets isOpen to false PhoneWindow will be in to an
inconsistent state.

Fixes bug 9404689.

Change-Id: If0129a0859546b35445df0f4be2f422c4807fba7