Gardening: mark fast/dom/document-contentType-data-uri.html as failed

BUG=370789
TBR= dcheng
NOTRY=true

Review URL: https://codereview.chromium.org/267353003

git-svn-id: svn://svn.chromium.org/blink/trunk@173490 bbb929c8-8fbe-4397-9dbb-9b2b20218538