Remove shend@ from css/ and style/ OWNERs.

No longer working on CSS.

Change-Id: I19305cdece49cce61f56225bc3e4774eb114d590
Reviewed-on: https://chromium-review.googlesource.com/c/1287269Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600593}

third_party/blink/renderer/core/css/OWNERS

 andruud@chromium.org
 ericwilligers@chromium.org
-shend@chromium.org
 
 # Also core owners
 alancutter@chromium.org

third_party/blink/renderer/core/style/OWNERS

 andruud@chromium.org
 ericwilligers@chromium.org
-shend@chromium.org
 
 # Also core owners
 alancutter@chromium.org