Revert "Make Function.length and Function.name configurable properties."

Plenty of test failures on test262, Mozilla, Webkit. Will have to investigate.

TBR=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/139983003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19203 ce2b1a6d-e550-0410-aec6-3dcde31c8c00