Exclude background-repeat from comprasion when styling the controls.

This helps it retain native styling.

BUG=229683

Review URL: https://chromiumcodereview.appspot.com/14776012

git-svn-id: svn://svn.chromium.org/blink/trunk@151537 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed