Use resize events as proxy for orientation change

Crosswalk doesn't return a usable value for window.orientation
on Android, which the app was previously relying on to determine
portrait/landscape.

It also seems as though Crosswalk Android isn't firing
orientationchange events, even though "onorientationchange" is
present in the window object.

(see https://github.com/crosswalk-project/crosswalk/issues/648 for
the related Crosswalk bug)

Consequently, orientation changes weren't being detected.

By forcing fallback to resize events, and comparing window
height/width, we "simulate" orientationchange events to work around
these issues.

Fixes #2