Disable WebViewTest.AutoSizeSW which is flaky on XP bots.

TBR=fsamuel@chromium.org
BUG=299507

Review URL: https://codereview.chromium.org/25639002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226341 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226341