Test flakiness fix for mouseover-mouseout

Since test output dumped as text it can't put space for boxes.
So removed space from expectation file.

BUG=305346

Review URL: https://codereview.chromium.org/567533002

git-svn-id: svn://svn.chromium.org/blink/trunk@182582 bbb929c8-8fbe-4397-9dbb-9b2b20218538