Relax test expectations in BootUpMemoryUse.

R=dcarney@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11738004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13293 ce2b1a6d-e550-0410-aec6-3dcde31c8c00