ES3 specified that functions created via Function() would have
enumerable prototypes, unlike function literals.  For this reason, V8
has always had two prototypes for functions: "function_map" for
literals, and "function_instance_map" for "function instances": those
functions created by Function().

However, since 2009 or so, both maps have been the same!  Both have had
writable, non-enumerable prototypes.  Moreover, ES5 changed to specify
that function instances would have non-enumerable prototypes.

This patch removes the separate maps for function instances in sloppy
and strict mode.

R=mstarzinger@chromium.org
TEST=mjsunit/function-prototype
BUG=

Review URL: https://codereview.chromium.org/14829005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14619 ce2b1a6d-e550-0410-aec6-3dcde31c8c00