Compare tooltip right offset to viewport right offset (and not width)

Created by: Intrepidd

Hi !

There seems to be a bug on viewport bound check.

Instead of checking that the right offset of the tooltip is not bigger than the right offset of the viewport, you check it's not bigger to the viewport size. This causes wrong offsets being applied in some conditions.

I'm willing to add a unit test if you acknowledge this issue but this will be complicated as qunit tests run in a div with a negative positionning, that will prevent the bug from happening.

Thanks