Use Window::get_cx() in DocumentFragment::Constructor.
auto merge of #1059 : SimonSapin/servo/newnewcss, r=kmcallister

Some progress on #1006 and #1057.
auto merge of #1058 : Ms2ger/servo/get_cx-followup, r=jdm

These changes landed in parallel.
Remove View type parameter from DocumentType
auto merge of #1048 : ttaubert/servo/documenttype, r=jdm

This should fix #1046.
Handle th tag as HTMLTableCellElement. #1060
auto merge of #1061 : saneyuki/servo/th, r=larsbergstrom
Implement HTMLTableDataCellElement & HTMLTableHeaderCellElement.
auto merge of #1063 : saneyuki/servo/th, r=jdm
CSS: separate cascading from selector matching, add style attributes.