Scroll parent, only need overflowX or overflowY

[thonglh]

To get scroll parent, we are checking for overflow, overflowX, overflowY to match (scroll|auto).
This leads to some issues:

• For Chrome (I have not checked in the other browser), node.getComputedStyle() will always return empty string for overflow attribute
  So for now, scrollParent(node) always return document.
• For some reason, we only allow the container to be overflow in one direction and hidden in the other, eg:

overflow-x: hidden;
overflow-y: auto;

This setting will not allow the container to be detected as scrollParent, and this is bad

[thonglh]

cc @jasonslyvia
Please help!

[vinhlh]

yo yo, any update on these PRs. Love to see this merged.

[ameerthehacker]

@thonglh I believe this is a duplicate PR for #167