* Facility for generating a node several ways.  This allows
  code to be generated for a node knowing where it is trying
  to match relative to the 'current position' and it allows
  code to be generated that knows where to backtrack to.  Both
  allow dramatic reductions in the amount of popping and pushing
  on the stack and the number of indirect jumps.
* Generate special backtracking for greedy quantifiers on
  constant-length atoms.  This allows .* to run in constant
  space relative to input string size.
* When we are checking a long sequence of characters or character
  classes in the input then we do them right to left and only the
  first (rightmost) needs to check for end-of-string.
* Record the pattern in the profile instead of just <CompiledRegExp>
* Nodes no longer contain an on_failure_ node.  This was only used
  for lookaheads and they are now handled with a choice node instead.
Review URL: http://codereview.chromium.org/12900

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@930 ce2b1a6d-e550-0410-aec6-3dcde31c8c00