Added preliminary implementation of ES Harmony weak maps.  Weak maps can be enabled by the flag --harmony_weakmaps.

Introduced a toplevel Makefile to support GYP-based building.  GYP can be found at http://gyp.googlecode.com.

Fixed a bug in the length property of functions created by Function.prototype.bind.

Reduced malloc heap allocation on process startup.

Several important code generation bug fixes.

Performance improvements on all platforms.

git-svn-id: http://v8.googlecode.com/svn/trunk@8874 ce2b1a6d-e550-0410-aec6-3dcde31c8c00