Streamline the code for patching optimized code for lazy deopt.

Streamline the code for patching optimized code for lazy deopt.

Rewrite the lazy deopt patching code on IA32 to use addresses throughout,
rather than offsets and a base address.

Also, rename a couple of ambiguous Code fields from _start to _offset.

Review URL: http://codereview.chromium.org/6334083

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00