Prevent NPE during ion-slide-box drag

[jayproulx]

Uncaught TypeError: Cannot read property 'contains' of undefined ionic.bundle.js:6182
ionic.views.ListView.ionic.views.View.inherit._getItem ionic.bundle.js:6182
ionic.views.ListView.ionic.views.View.inherit._startDrag ionic.bundle.js:6223
ionic.views.ListView.ionic.views.View.inherit._handleDrag ionic.bundle.js:6266
(anonymous function) ionic.bundle.js:6088
triggerEvent ionic.bundle.js:769
dragGesture ionic.bundle.js:1804
detect ionic.bundle.js:1347
bindDomOnTouch ionic.bundle.js:896

[jayproulx]

I've noticed quite a few instances of target.classList.contains and e.target.classList.contains, which are at risk of the same issue. This PR is only for my current ion-slide-box implementation.

[ajoslin]

Thanks @jayproulx - merged!

[jayproulx]

I notice that a gulp build outputs to dist and not release, what's the correct way to update the release build to pick up the latest fixes?

Right now I'm doing a bower install github/driftyco/ionic#commit, I could bower install from my PR fork and copy dist over release but I'm not sure if there's a better way.

[ajoslin]

You have to bower install driftyco/ionic-bower#master - our ionic repo only holds stable releases right now unfortunately, since bower does not let us point to the new ionic-bower repo yet.

[jayproulx]

Thanks @ajoslin