Blink core owners should own build/scripts/core

in order to increase the number of owners of build/scripts/core/css/.

Change-Id: I36f2b7931b2d475a9fc4405088d61a5efccc45d6
Reviewed-on: https://chromium-review.googlesource.com/949804Reviewed-by: nainar <nainar@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541034}

third_party/WebKit/Source/build/scripts/core/OWNERS

+set noparent
+file://third_party/WebKit/Source/core/OWNERS
+
+# TEAM: blink-dev@chromium.org
+# COMPONENT: Blink

third_party/WebKit/Source/build/scripts/core/css/OWNERS

-set noparent
 file://third_party/WebKit/Source/core/css/OWNERS
 
 nainar@chromium.org