Group property assignments in top-level blocks.

Group property assignments in top-level blocks.

This patch enables insertion of To{Slow,Fast}Properties around a group
of assigments to the same object even when they are put in a block
(e.g. try-catch, if, etc.). Catching exceptions and disabling parts of
code based on some config vars is rather common in top-level code.

R=vegorov@chromium.org

Review URL: http://codereview.chromium.org/7314002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8558 ce2b1a6d-e550-0410-aec6-3dcde31c8c00