Remove offset() and is_in_object() from hydrogen and lithium LoadNamedField and StoreNamedField and use the appropriate methods on HObjectAccess instead

BUG=

Review URL: https://codereview.chromium.org/15881003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14806 ce2b1a6d-e550-0410-aec6-3dcde31c8c00