Make the test land in r143482 less platform-specific

Add outline:none to the test so platform-specific outlines don't kick in and
make us require separate results for Mac and Linux.

Unreviewed, gardening.

* fast/repaint/paint-caret-in-div-with-negative-indent-expected.png:
* fast/repaint/paint-caret-in-div-with-negative-indent.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143495 268f45cc-cd09-0410-ab3c-d52691b4dbfc