Clean-up and repair cumulative marking and sweeping time stats.

BUG=
R=ernstm@chromium.org

Review URL: https://codereview.chromium.org/432743002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22777 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
X87: Land the Fan (disabled)

port r22709.

This patch only covers the code change of orginal X87 port.
For the changes under ./src/compiler/ and ./tools/gyp/v8.gyp file,
I will submit it in another seperate patch.

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/430423002

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

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22778 ce2b1a6d-e550-0410-aec6-3dcde31c8c00