Revert "Split ColumnRule field in ComputedStyle."

This reverts commit f50e2dcfad8c3e03eb9445243e4b5e8fccf15b87.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> 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}

TBR=nainar@chromium.org,shend@chromium.org

Change-Id: I6a21392b25ada865384bb358f5bfd1205fd20488
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 628043
Reviewed-on: https://chromium-review.googlesource.com/544442
Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481469}
3 files changed