Make Document::root private, in preparation for removing it as part of making Document a Node.
auto merge of #1051 : Ms2ger/servo/private-root, r=jdm

In preparation for removing it as part of making Document a Node.
Use Window::get_cx() in DocumentFragment::Constructor.
Add a new 'style' crate. (Empty for now.)
Move the content of 'script/style' into the new 'style' crate.
Flat is better than nested.
Add the margin and padding shorthands.
Change the range of percentages to 0..1 in specified and computed values.
Restore the font shorthand, accidentally dropped in commit 622bc5705c
Add CSS parser support for 'vertical-align'.
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
Add line breaks for readability.
Rename the element field of the DOM Node hierarchy.

See #924