Improve load IC so it can call a native accessor even if the holder is

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.
Review URL: https://chromiumcodereview.appspot.com/10831153

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12264 ce2b1a6d-e550-0410-aec6-3dcde31c8c00