Update test expectations for dynamic-stylesheet-loading.html

virtual/web-animations-css/animations/dynamic-stylesheet-loading.html times out on Linux

BUG=277005
TEST=none
TBR=steveblock@chromium.org

Review URL: https://codereview.chromium.org/22980025

git-svn-id: svn://svn.chromium.org/blink/trunk@156485 bbb929c8-8fbe-4397-9dbb-9b2b20218538