o.x() and o[expr]()

other changes:
- Fix missing relocation info for StoreIC on global object.
- Generate only one common return sequence instead of always appending 
  "return <undefined>" at the end of each function: The first JS 
  return-statement will generate the common return sequence. All
  other return-statements will generate a unconditional branch to the common
  return sequence.


Review URL: http://codereview.chromium.org/340037

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3183 ce2b1a6d-e550-0410-aec6-3dcde31c8c00