Remove entries from TestExpectations that were copied into test_expectations_w3c.txt.

This is in preparation for rolling to a new version of the W3C repos.

TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/226583002

git-svn-id: svn://svn.chromium.org/blink/trunk@170924 bbb929c8-8fbe-4397-9dbb-9b2b20218538