port r22680

original commit message:

  only generate a single normal IC per kind per slow-mode map.

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/423393003

Patch from Chunyang Dai <chunyang.dai@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22697 ce2b1a6d-e550-0410-aec6-3dcde31c8c00