X87: Move state sentinels into TypeFeedbackVector.

X87: Move state sentinels into TypeFeedbackVector.

port r24037.

original commit message:

  Move state sentinels into TypeFeedbackVector.

  These sentinels were in the wrong place, living in only tangentially related class TypeFeedbackInfo, but they codify state in the TypeFeedbackVector.

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/585743002

Patch from Jing Bao <jing.bao@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24062 ce2b1a6d-e550-0410-aec6-3dcde31c8c00