virtual/windows-directwrite/fast/text/sub-pixel/text-scaling-pixel.html is no longer flaky

Remove flaky expectations for virtual/windows-directwrite/fast/text/
sub-pixel/text-scaling-pixel.html as it is no longer flaky.

TBR=jsbell@chromium.org

Review URL: https://codereview.chromium.org/259273002

git-svn-id: svn://svn.chromium.org/blink/trunk@172871 bbb929c8-8fbe-4397-9dbb-9b2b20218538