Lithium codegen should not pass around block_ids. Rather encapsulate the basic block to assembly label mapping in the LInstruction.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/17276002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15235 ce2b1a6d-e550-0410-aec6-3dcde31c8c00