Do not perform from-by animations for non-additive attributes.

Cherry-pick from https://bugs.webkit.org/show_bug.cgi?id=113224

BUG=231408

Review URL: https://chromiumcodereview.appspot.com/23983038

git-svn-id: svn://svn.chromium.org/blink/trunk@157846 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Delete http/tests/inspector/layer-navigation.html

This test is super flaky.  It's not really providing any test coverage.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=http%2Ftests%2Finspector%2Flayer-navigation.html

TBR=caseq@chromium.org

Review URL: https://codereview.chromium.org/23601036

git-svn-id: svn://svn.chromium.org/blink/trunk@157847 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Restore file I removed by accident.

Review URL: https://codereview.chromium.org/24105004

git-svn-id: svn://svn.chromium.org/blink/trunk@157849 bbb929c8-8fbe-4397-9dbb-9b2b20218538