Reorder code in fast-codegen-ia32.cc.

Reorder code so that helper functions and simple accessors come before
all the visit function.

Review URL: http://codereview.chromium.org/650026

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3912 ce2b1a6d-e550-0410-aec6-3dcde31c8c00