Refine fast/text/international/rtl-space-in-ltr-element.html expectation -> ImageOnlyFailure

TBR=eae

Review URL: https://codereview.chromium.org/183883014

git-svn-id: svn://svn.chromium.org/blink/trunk@168379 bbb929c8-8fbe-4397-9dbb-9b2b20218538