DevTools: gardening: mark inspector/editor/text-editor-word-jumps.html as Slow

BUG=420008
TBR= lushnikov@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/629983003

git-svn-id: svn://svn.chromium.org/blink/trunk@183267 bbb929c8-8fbe-4397-9dbb-9b2b20218538