Store border-*-style on SurroundData in ComputedStyle

This patch moves the storage of border-*-style away from BorderStyle.
We instead store them on the generated SurroundData group on
ComputedStyle instead.

We generate a BorderValue to pass to Layout in
ComputedStyle from all the border information stored
there.

Diff: https://gist.github.com/nainar/fd091fc658aebc3f5676f16e545e975a/revisions

BUG=628043

Review-Url: https://codereview.chromium.org/2880573002
Cr-Commit-Position: refs/heads/master@{#472999}
11 files changed