fixed: first reposition, then autofocus

to prevent document scrolling on focus() call
fixed: finding element to autofocus

added check if element has children, before trying to traverse through
them
fixed: finding element to autofocus
Merge branch 'master' of https://github.com/GoogleChrome/dialog-polyfill

Conflicts:
	dialog-polyfill.js
Merge pull request #16 from ThiRaBrTNK/master

fixed: first reposition, then autofocus