Menu swiping mess (push and reveal only)

[manucorporat]

Short description of the problem:

This happens because both menus are capturing the sliding events at the same time.

Just in case, this bug was not caused by 29791f8

menu canStart, left isOpen false angle 0 distance 18
menu gesture, onSlideBeforeStart left
keyboard close()
menu canStart, right isOpen true angle 0 distance 18
menu gesture, onSlideBeforeStart right
keyboard close()
menu gesture, onSlide left distance 10 min 0 max 304 z 304 stepValue 0.03289473684210526
menu gesture, onSlide right distance -294 min -304 max 0 z -304 stepValue 0.9671052631578947
Menu is being dragged 0.03289473684210526
menu gesture, onSlide left distance 21 min 0 max 304 z 304 stepValue 0.06907894736842106
menu gesture, onSlide right distance -283 min -304 max 0 z -304 stepValue 0.930921052631579
Menu is being dragged 0.06907894736842106
menu gesture, onSlide left distance 31 min 0 max 304 z 304 stepValue 0.10197368421052631
menu gesture, onSlide right distance -273 min -304 max 0 z -304 stepValue 0.8980263157894737
Menu is being dragged 0.10197368421052631
(....)

Overlay menus are not affected because they use the backdrop component and it prevents the other menu from capturing the events. Using a backdrop always (a transparent one) could be a potential fix.

Another option is to get access to the MenuController from the GestureController, so we know if there are more menus opened.
@adamdbradley what do you think? I like the MenuController solution, but it sounds like a very coupled logic...

Steps to reproduce:

1. Open a /dist/e2e/menu/basic
2. Simulate a narrow screen (iPhone)
3. Open a right menu
4. Now try to open the left menu

Which Ionic Version? 2.x