Many fixes to v8 for tilegx to pass all tests and support node.js.

This version is based on v8-3.18.5 with some fixes from later versions
pulled in.  Also, some older (obsolete) API entry points were re-added
to allow this to work with node.js v0-10.29.

All v8 tests now pass, except for a small set which are understood and
acceptable.  See README.tilegx.