This is a refactoring-only CL and the first one in a series for enabling
inlining of accessors. The naming and argument order has been unified a bit, and
some tests have been pushed to the caller in order to get a simpler
signature. Note that the latter temporarily introduces some code redundancy, but
this will be cleaned up in one of the next CLs.

Review URL: https://chromiumcodereview.appspot.com/10826028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12198 ce2b1a6d-e550-0410-aec6-3dcde31c8c00