Cleaned up runtime macros a bit.

The bulk of this CL is purely mechanical: Make the CONVERT_FOO macros more
uniform by always using an index instead of an object. Apart from this, it
includes a few minor changes like using CONVERT_SMI_ARG_CHECKED a bit more or
introducing a new macro for PropertyDetails. Nothing spectacular, just something
sitting on my disk for quite some time now...

Review URL: https://chromiumcodereview.appspot.com/9395075

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10772 ce2b1a6d-e550-0410-aec6-3dcde31c8c00