Enyo-964 Add guard code for initail state which window.history doesn't have any state.
Enyo-964 Add guard code for initail state which window.history doesn't have any state.

Enyo-DCO-1.1-Signed-off-by: David Um david.um@lge.com

mcanthony/moonstone,mcanthony/moonstone,mcanthony/moonstone,enyojs/moonstone