Split ColumnRule field in ComputedStyle.

Currently, column-rule related properties are being stored as a single
BorderValue called ColumnRule. However, it is possible to split
ColumnRule into its constituent fields and generate each of them
individually.

There should be no performance impact from this patch.

Diff: https://gist.github.com/3b5a55b0cedff7b4d7b9c1b196faf5a9/revisions

Bug: 628043
Change-Id: I04fe9e7f3c9221614870f7de0b2f1c05c023ee4a
Reviewed-on: https://chromium-review.googlesource.com/544415
Commit-Queue: Darren Shen <shend@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481468}
3 files changed