Fix touchless.css

Previously, we hadn't applied this style via LayoutTheme, but this
appears to be normative (cf. mac.css).

touchless.css also contained a universal rule, which tripped a
DCHECK, and I've also slightly qualified it in this CL.

Bug: 961026
Change-Id: I0626299f7dee1c0c5a8b04e506d6feae05f80663
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600960
Commit-Queue: Ian Vollick <vollick@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659192}