Disable memory_test reference tests on mac.

BUG=323765
TBR=isherman@chromium.org,ernstm@chromium.org

Review URL: https://codereview.chromium.org/90483002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237548 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237548