Combine it with the `borderStyle` variable, since it's only used once, and move it closer to the code using it. This is a small clean up in preparation of changing Color to StyleColor.
<rdar://problem/100199385>
Pull request: https://github.com/WebKit/WebKit/pull/4553
Committed 254703@main (137ee9c4498d): <https://commits.webkit.org/254703@main> Reviewed commits have been landed. Closing PR #4553 and removing active labels.