This CL is a step towards removing ZoneObject's new operator without a Zone
parameter, which uses Isolate::Current. For e.g. the bulletben benchmark, this
CL reduces the number of calls to this new operator by roughly 120k, but we are
still left with 780k calls from other sites...

Review URL: https://chromiumcodereview.appspot.com/9487010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10860 ce2b1a6d-e550-0410-aec6-3dcde31c8c00