fix(tooltip): fix undefined element when triggering multiple times in fa...

...st sequence (like described in #1243)

Clicking multiple times fast on the dropdown button in docs was causing an exception because the element references were being cleaned up in 'hide' animation callback. When the show/hide calls were executed in specific timming, the 'hide' callback was being run after calling 'show' which caused the $isShown flag to be true but the element to be destroyed.

By calling 'destroyTipElement' only in 'show' before creating a new one, we avoid this issue with no noticable impact on allocated resources.