The double to i convertion should round to zero not infinity.

Thes bug was revealed by http://codereview.chromium.org/6597003, where the value of (x * 1.0000000001) | 0 was x - 1 and not x when x was a negative smi.

I will not commit http://codereview.chromium.org/6597003 before this is committed.

TEST=test/mjsunit/smi-ops-inlined.js
Review URL: http://codereview.chromium.org/6594008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6951 ce2b1a6d-e550-0410-aec6-3dcde31c8c00