Disable PrerenderBrowserTest.PrerenderDelayLoadPlugin

TBR=cbentzel@chromium.org
NOTRY=true
BUG=306715

Review URL: https://codereview.chromium.org/27084002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228305 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228305