Various improvements regarding the way we print code code comments.

Various improvements regarding the way we print code code comments.

* All Lithium instructions have an associated Hydrogen instruction now,
  simplifying things.

* Consistently print <Lithium instruction number,Hydrogen value id> prefixes.

* Do not print uninteresting Lithium instructions like empty gaps, jumps to the
  next instruction, etc.

* Removed special handling of HChange-like instructions, it is totally unclear
  why they had this special treatment. If we really want to print more
  information about Lithium instructions, we should do it in a totally way,
  anyway (e.g. by unifying things with the generation of hydrogen*.cfg files).

* Made deferred code and the jump table stand out a little bit more.

* Print info about special blocks like loop headers and OSR entries.

Review URL: https://codereview.chromium.org/14371005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14370 ce2b1a6d-e550-0410-aec6-3dcde31c8c00