the code generator.

The runtime function checks if it needs to create a boilerplate
object or if it can clone from an existing boilerplate.

This is already done in the top-level compiler. 

Review URL: http://codereview.chromium.org/507036

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3516 ce2b1a6d-e550-0410-aec6-3dcde31c8c00