MIPS: Improve load IC so it can call a native accessor even if the holder is in dictionary mode. Add a flag to all maps to indicate whether they are used for dictionary (normalized) objects or fast mode objects.  This is a commit of https://chromiumcodereview.appspot.com/10826213/ for palfia. This is a port of r12264, https://chromiumcodereview.appspot.com/10831153

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12290 ce2b1a6d-e550-0410-aec6-3dcde31c8c00