Set test back to ImageOnlyFailure.
Set test back to ImageOnlyFailure.

In order to land first-letter as a pseudo element I had to set the virtual
test for slimming plaint lineboxcontain/glyph.html to manual rebaseline.
Now that the real rebaselines have landed, this can be set back to ImageOnlyFailure.

BUG=391288
TBR=leviw@chromium.org

Review URL: https://codereview.chromium.org/734703002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@185457 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs