Fix node 0.11 incompatibility in w3c test harness.
Fix node 0.11 incompatibility in w3c test harness.

The rewritten `vm` package in node 0.11 doesn't create a new unique
context for every call to vm.createContext(foo) any more; instead it
just "contextifies" foo. This caused confusion as every test suite was
sharing the same context.

Do a shallow clone into the context to fix the issue.

fgnass/domino,cristianosistemas/domino,cscott/domino,arlolra/domino,cristianosistemas/domino,cscott/domino,modulexcite/domino,modulexcite/domino,arlolra/domino,modulexcite/domino,cristianosistemas/domino,jazdw/domino,fgnass/domino