[NaCl SDK] nacl_io: Add fakes for more types of PP_Var.

Add fakes for VAR_ARRAY and VAR_ARRAY_BUFFER

R=binji@chromium.org

Review URL: https://codereview.chromium.org/137853023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245696 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245696